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Prof. Dr. T. Jüstel, Münster University of Applied Sciences, Germany Slide 1
Design and Degradation of UV Emitting
Luminescent Materials for Xe Excimer
Discharge Lamps
Thomas Jüstel & Mike Broxtermann
RG Tailored Optical Materials
Institute for Optical Technologies
Münster Univ. of Applied Sciences
University Stuttgart
@ January 30th, 2018
Prof. Dr. T. Jüstel, Münster University of Applied Sciences, Germany Slide 2
Ozone layer
Va
cu
um
UV
UV
-C
UV
-B (
280
–300 n
m)
UV
-A &
UV
-B (
300
–320 n
m)
1.37 kW/m2
Classification and impact ofUV Radiation (100 - 380 nm)
Vacuum UV (100 - 200 nm)• Photolysis of water• Cleavage of N2 and O2
• Ozone formation
UV-C (200 - 280 nm) & UV-B (280 - 300 nm)• Ozone cleavage
UV-B (300 - 320 nm) &UV-A (320 - 380 nm)• Photochemical
degradation of airpollutants
• Disinfection at photo-catalytically active sites
Prof. Dr. T. Jüstel, Münster University of Applied Sciences, Germany Slide 3
Contents
1. Motivation
2. Chemistry and Physics of Luminescent Materials
3. UV Radiation Sources
4. Xe Excimer Discharge Lamps
5. VUV to UV Converter - Design
6. Phosphor Converted Xe Excimer Lamps - Degradation
7. Spin-off: Nanoscale UV Phosphors
8. Summary & Outlook
Prof. Dr. T. Jüstel, Münster University of Applied Sciences, Germany Slide 4
1. MotivationOngoing increase ot water consumption and pollution
• UV-C Radiation (265 nm) inactivates micro organisms
due to DNA modification
• VUV Radiation (180 - 200 nm) oxidizes due to
H2O cleavage into radical species
Industrial installations → discharge lamps
Mobile devices → discharge lamps or LEDs
Wat
er
consu
mption / 1
09
m3
0
1000
2000
3000
4000
5000
6000
1900 1950 2000 2050Year
Agriculture
Industry
Household
Total
Prof. Dr. T. Jüstel, Münster University of Applied Sciences, Germany Slide 5
1. Motivation
Water impurities
• Microorganisms: Bacteria, viruses, spores, …
• Chemical (micro)pollutants: Toxic, bioactive, or non-
biodegradable organic compounds, NO3-
• Micro & nanoplastics “Great Pacific Garbage Patch”
Trend to apply green chemistry for water treatment
• Avoid use of toxic/ hazardous substances (Cl2, ClO2, NaOCl)
• Convert total organic compounds (TOC) to CO2 and H2O
• Introduce energy efficient and sustainable processes
• Biochemistry → Microorganism design, genetics
• Catalysis → Catalytic pigments and coatings
• Photochemistry → Frequency selective radiation sources
• Solar chemistry → Solar radiation + converter
• Fast analytics → Optical spectroscopy using radiation
sources switchable in the ns-range
Ongoing increase ot water consumption and pollution
Prof. Dr. T. Jüstel, Münster University of Applied Sciences, Germany Slide 6
2. Chemistry and Physics of LMsA luminescent material (phosphor) converts absorbed energy into
electromagnetic radiation beyond thermal equilibrium
Host• Coordination number and geometry• Symmetry of activator sites• Optical band gap• Phonon spectrum
Dopants, impurities, and defects• Concentration• Phase diagram and miscibility gaps
Particle surface• Zeta-potential• Surface area• Coatings Light in- and outcoupling
Particle morphology• Shape• Particle size distribution
Eu2+
Eu2+
Eu2+
Mn2+
VO
Prof. Dr. T. Jüstel, Münster University of Applied Sciences, Germany Slide 7
Temp. dependent PL of selected
LMs upon 254 nm excitation
2. Chemistry and Physics of LMs
250 300 350 400 450 500 550 600 650 700 750 800
0,0
0,2
0,4
0,6
0,8
1,0 PRO-2009-AB-012 ex307nm
PRO-2009-AB-012 mon656nm
Rela
tive in
tensity [a.u
.]
Wavelength [nm]
656 nm
0 100 200 300 400 500
0,0
0,2
0,4
0,6
0,8
1,0 LiEuMo2O
8
Ideal
YAG:Ce U728
No
rm. em
issio
n in
teg
rals
[a.u
]
Exc. density [W/mm2]
0 2000 4000 6000 8000 100001
10
100
1000
Decay Measurement
Inte
ns
ity
[c
ou
nts
]
time [ns]
T=100.00 K
T=150.00 K
T=200.00 K
T=250.00 K
T=300.00 K
T=350.00 K
T=400.00 K
T=450.00 K
T=500.00 K
Linearity of YAG:Ce
and LiEuMo2O8
Excitation and emission
spectrum of Mg2TiO4:Mn
Decay curves of
SrSi2N2O2:Eu
Relevant physical properties
PL spectra
CIE colour point
Luminous efficacy
Quantum yield (QY)
Colour point consistency
Decay curve
Thermal quenching
Linearity
Stability under operation
Prof. Dr. T. Jüstel, Münster University of Applied Sciences, Germany Slide 8
Quenching and degradation mechanisms
Reversible quenching
• Thermal quenching at high temperature
• Saturation at high power density
Irreversible degradation
• Dissolution/decomposition in applicat. medium BaSi2O5:Pb2+
• Thermal oxidation or reduction of the activator LaPO4:Ce3+
• Photo oxidation or reduction of the activator BaMgAl10O17:Eu2
• Reactions with the glass wall (Y,Gd)BO3:Tb3+
• Reaction with discharge species, e.g. Hg or Xe Zn2SiO4:Mn2+
• Hydrolysis by moisture YF3:Pr3+
Choose chemically stable and radiation hard host
& activator e.g. Lu3Al5O12:Gd3+ (L80 >> 10000 h!)
Otherwise: Particle coatings or lower activator conc.
2. Chemistry and Physics of LMs
300 400 500 600 700 8000
20
40
60
80
100
BaSi2O5:Pb from suspension
BaSi2O5:Pb from production
Re
fle
cta
nce
[%
]
Wavelength [nm]
Prof. Dr. T. Jüstel, Münster University of Applied Sciences, Germany Slide 9
Overview
Solar radiation > 300 nm
Hg discharge lampslow-pressure 185, 254 nmamalgam 185, 254 nmmedium-pressure 200 – 400 nm
Xe discharge lamps 230 – 800 nmD2 discharge lamps 110 – 400 nm
Excimer laser 193 nmSolid state laser Nd3+ 4th harmon. 266 nm
Excimer discharge lampsXe2* 172 nmKrCl* 222 nmXeBr* 282 nmXeCl* 308 nm
(Al,Ga)N LEDs 210 – 365 nm(In,Ga)N LEDs 365 – 400 nm
3. UV Radiation Sources
Prof. Dr. T. Jüstel, Münster University of Applied Sciences, Germany Slide 10
Solar Radiation
~ 5% UV ~ 60% VIS ~ 35% IR
The solar spectrum depends on daytime & season,
air pressure, clouds, particles (dust) and so on
AM
0A
M1
.0
Earth‘s surface
0,0
0,2
0,4
0,6
0,8
1,0
500 1000 1500 2000 2500 3000 3500 4000
Black Body (T = 5800 K)
0,0
0,2
0,4
0,6
0,8
AM0 (extraterrestric)
No
rmali
sed
em
issio
n in
ten
sit
y [
a.u
.]
500 1000 1500 2000 2500 3000 3500 4000
0,0
0,2
0,4
0,6
0,8 AM1.5 (48.2 ° angle)
Wavelength [nm]
O2
O3
H2O
CO2
CO2
<400 400-500 500-600 600-700 >700
37.8 W/m² 130.4 W/m² 144.6 W/m² 134.0 W/m² 269.2 W/m²
5.3% 18.2% 20.2% 18.7% 37.6%
3. UV Radiation Sources
48.2°
Prof. Dr. T. Jüstel, Münster University of Applied Sciences, Germany Slide 11
Direct radiation: Diffuse radiation:Filtered solar radiation Scattered solar radiation
CCT = 5500 - 6500 K CCT = 10600 K
50 W/m2 UV total and 0.1 W/m2 UV-B almost no UV radiation
~ 1000 W/m2 ~ 50 W/m2
3. UV Radiation Sources
Prof. Dr. T. Jüstel, Münster University of Applied Sciences, Germany Slide 12
Present trend: Use solar light & combine with traditional light sources,
e.g. for water, air, and surface disinfection or for indoor illumination
3. UV Radiation Sources
Prof. Dr. T. Jüstel, Münster University of Applied Sciences, Germany Slide 13
Low Pressure Hg Amalgam Medium Pressure Hg
UV-C wavelength 254 nm 254 nm 200 - 280 nm
Typical lamp power 4 ... 100 W 100 ... 300 W 1 ... 17 kW
Lamp efficiency < 40% 30 ... 35% 10 ... 15%
GAC factor 85% 85% 80%
UV-C power per length 0.2 W / cm 0.7 W / cm 15 W / cm
Wall temperature 40 °C 100 °C 600 - 800 °C
Selection based on application area and life cycle cost
Hg vapour discharge lamps - Overview
3. UV Radiation Sources
Hg lamp
invented
1904 for
Rachitis
therapy
Prof. Dr. T. Jüstel, Münster University of Applied Sciences, Germany Slide 14
„LED platform“
465 nm LEDs Illumination
410 nm LEDs Full conversion
365 nm LEDs Black light
265 nm LEDs Disinfection
375 400 425 450 475 500 525 375 400 425 450 475 500 525 550
Em
iss
ion
inte
ns
ity
(a
.u.)
Wavelength [nm]
diodesLaser
400nm
425nm
450nm
465nm
480nm
500nm
LEDs
„Laserdiode platform“
940 nm Remote control
785 nm CD
655 nm DVD
405 nm Blue ray DVD
LEDs and laser diodes
3. UV Radiation Sources
Prof. Dr. T. Jüstel, Münster University of Applied Sciences, Germany Slide 15
Ozone generator
(Wedeco AG)
Flat lamp
for LCD
Backlighting
(Osram AG)
Exhaust treatment
(Siemens AG)UV Radiation sources (Xenon)
Heraeus Noblelight
Triton
Osram Xeradex
Devices using a dielectric barrier excimer discharge (either O2 or Xe)
4. Xe Excimer Discharge Lamps
Prof. Dr. T. Jüstel, Münster University of Applied Sciences, Germany Slide 16
4. Xe Excimer Discharge Lamps
Lamp sketch and principle of working
p(Xe) = 300 mbar
P = 10 - 100 W
U = 3 - 5 kV
f = 10 - 50 kHz
Micro discharge
channel
Surface
discharge
Surface
discharge
Xe Xe*
Xe* + 2 Xe Xe2* + Xe
Xe2* 2 Xe + hν (172 nm)
hν (190 - 700 nm) = f(luminescent screen)
R(t)
CD
CD
CG
ignition
~
Prof. Dr. T. Jüstel, Münster University of Applied Sciences, Germany Slide 17
1st Continuum
2nd Continuum
Excimer highest excited state
Monomer
Ground states
Fast dissociation
Excited monomeric Xe species:
Emits 147 nm (8.44 eV)
Xe resonance line
1st Emission continuum:
148 nm (8.38 eV)
Xe2[0+
U(3P1)high n] Xe2[0+
g(1S0)]
152 nm (8.16 eV)
Xe2[1U(3P2)high n] Xe2[0+
g(1S0)]
2nd Emission continuum:
186 nm (7.38 eV)
Xe2[0+
U(3P1)low n] Xe2[0+
g(1S0)]
172 nm (7.21 eV)
Xe2[1U(3P2)low n] Xe2[0+
g(1S0)]
4. Xe Excimer Discharge Lamps
Xe and Xe2* energy levels and discharge emission spectrum
Prof. Dr. T. Jüstel, Münster University of Applied Sciences, Germany Slide 18
150 nm
172 nm
Lamp spectrum
Converter screen
Wavelength [nm]
147 nm 172 nm
Reso
nan
ce L
ine
Em
issio
n in
ten
sit
y 2n
dC
on
tinu
um
1s
tCo
ntin
uu
m
Lamp glass
150 nm
4. Xe Excimer Discharge Lamps
Xe excimer spectrum and typical lamp parameter
Example: Osram XERADEX L40/120/SB-S46/85
Power consumption = 20 W
Diameter = 4 cm
Length = 12 cm
Wall load ~ 0.15 W/cm2
Output power = 6 W
Power density = 0.04 W/cm2
Wall plug efficiency ~ 30% (including driver)
150 nm
Simplified reaction scheme
Xe(1S0) + e- Xe(3P1) + e-
Xe(3P1) Xe(1S0) + h147 nm
Xe(3P1) + 2 Xe Xe2(3u
+) + Xe
Xe2(3u
+) 2 Xe(1S0) + h172 nm
Prof. Dr. T. Jüstel, Münster University of Applied Sciences, Germany Slide 19
Host lattices
Fluorides Phosphates Borates Silicates Aluminates
Activator ions
Nd3+
Tl+, Pb2+, Pr3+, Bi3+
Gd3+, Bi3+, Pr3+, Ce3+
Tm3+, Pb2+, Ce3+, Eu2+
100 nm 200 nm 280 nm 320 nm 400 nm
UV-B UV-AUV-CVUV
5. VUV to UV Converter Design
UV Emitter - Suitable host lattices and activator ions
Prof. Dr. T. Jüstel, Münster University of Applied Sciences, Germany Slide 20
Pr3+ energy level scheme - Host impact
5. VUV to UV Converter Design
3H4
En
erg
y[1
03
cm
-1]
3H5
3H6
1S0
1D2
1G4
3P23P0
3F2
0
10
20
30
50
40
60[Xe]4f2 [Xe]4f15d1 Oh site distorted Oh site
3F3
3F4
3P1, 1I6
Prof. Dr. T. Jüstel, Münster University of Applied Sciences, Germany Slide 21
5. VUV to UV Converter Design
Pr3+ energy level scheme - Host impact1S0 –
2S+1LJ line emission
YF3:Pr
NaYF4:Pr
SrAl12O19:Pr
LaMgB5O10:Pr
LaB3O6:Pr
4f15d1 – 4f2 band emission
LiYF4:Pr 218 nm
YPO4:Pr 232 nm
KYF4:Pr 235 nm
YAlO3:Pr 245 nm
YBO3:Pr 263 nm
Lu2Si2O7:Pr 273 nm
Lu3Al5O12:Pr 310 nm
Y3Al5O12:Pr 320 nm
1D2-3HJ line emission
Y2O3:Pr 615 nm
CaTiO3:Pr,Na 615 nm
Blue emission
Red emission
UV band emission
UV line emission
213, 236
252, 271
407 nm
En
erg
y o
f the
low
est
cry
sta
l-field
co
mp
on
en
to
f [Xe]4
f15
d1
1D2
Prof. Dr. T. Jüstel, Münster University of Applied Sciences, Germany Slide 22
Pr3+ energy level scheme - Host impact
[Xe]4f15d1 – [Xe]4f2 vs. [Xe]4f2 – [Xe]4f2 emission
NaYF4:Pr3+ 213, 236 nm hexagonal CN 9 E([Xe]4f15d1) > E(1S0)
KYF4:Pr3+ 235 nm hexagonal CN 7 E([Xe]4f15d1) < E(1S0)
200 300 400 500 600 700 800
0,0
0,2
0,4
0,6
0,8
1,0KYF4:Pr3+
Inte
nsity [a
.u.]
Wavelength [nm]
Emission bei 160 nm
Anregung bei 232 nm
Reflexion
200 300 400 500 600 700 800
0.0
0.2
0.4
0.6
0.8
1.0
NaYF4:Pr3+
Inte
nsity [a.u
.]
Wavelength [nm]
Emission bei 160 nm
Anregung bei 272 nm
Reflexion
5. VUV to UV Converter Design
Prof. Dr. T. Jüstel, Münster University of Applied Sciences, Germany Slide 23
100 200 300 400 5000,0
0,2
0,4
0,6
0,8
1,04f
15d
1
Host
lattice
3F
J
3H
6
3H
5
3H
4
Wavelength [nm]
Distorted
dodecahedra
CN = 8
Y-O distances
4 x 2.24 Å
4 x 2.24 Å
CF splitting
~ 12000 cm-1
Centroid shift
~ 9600 cm-1
CFS and centroid shift reduces energy
of lowest crystal-field component of the
[Xe]4f15d1 configuration by ~ 22000 cm-1
E(4f15d1) below E(1S0)
[Xe]4f15d1 - [Xe]4f2 band emission
Situation in YPO4
(Eg = 9.0 eV)
5. VUV to UV Converter Design
Pr3+ energy level scheme - Impact of the host
Prof. Dr. T. Jüstel, Münster University of Applied Sciences, Germany Slide 2430.01.2018
Converter for differnet Xe excimer radiator applications
1. Water splitting and NOx removal
YPO4:Nd 190 nm
2. Mineralisation of µ-pollutants: Pharmaceuticals, hormones, …
YPO4:Bi 241 nm
YPO4:Pr 235 nm
LaPO4:Pr 225 nm
CaSO4:Pr,Na 218 nm
3. Disinfection: Water, surfaces, air, …
YPO4:Bi 241 nm
CaLi2SiO4:Pr,Na 252 nm
YBO3:Pr 265 nm
Y2Si2O7:Pr 275 nm
4. Photopolymerisation: UV curing
Lu3Al5O12:Gd 311 nm
LaMgAl11O19:Gd 311 nm
Y3Al5O12:Pr 320 nm
5. VUV to UV Converter Design
Prof. Dr. T. Jüstel, Münster University of Applied Sciences, Germany Slide 25
5. VUV to UV Converter Design
150 200 250 300 350 400 450 500 550 600 650 700 750 800
8,3 6,2 5,0 4,1 3,5 3,1 2,8 2,5 2,3 2,1 1,9 1,8 1,7 1,5
3F
J
3H
6
3H
4
Energy /eV
Inte
nsity (
no
rm.)
Wavelength /nm
172
nm
YPO4:PrExc.: 160 nm
Em.: 233 nm
Germicidal efficiancy (DIN 5031-10): 60.6%
4f15d
1
3H
5
0,0
0,1
0,2
0,3
0,4
0,5
0,6
0,7
0,8
0,9
1,0
Re
fle
cta
nce
/ %
Ba
SO
4
150 200 250 300 350 400 450 500 550 600 650 700 750 800
8,3 6,2 5,0 4,1 3,5 3,1 2,8 2,5 2,3 2,1 1,9 1,8 1,7 1,5
1S
0
1P
1/3P
2/3P
1
Energy /eV
Inte
nsity (
norm
.)
Wavelength /nm
17
2 n
m
Germicidal efficiancy (DIN 5031-10): 43.8%
YPO4:BiExc.: 160 nm
Em.: 260 nm
3P
1
MMCT
0
10
20
30
40
50
60
70
80
90
100
Reflecta
nce / %
BaS
O4
150 200 250 300 350 400 450 500 550 600 650 700 750 800
8,3 6,2 5,0 4,1 3,5 3,1 2,8 2,5 2,3 2,1 1,9 1,8 1,7 1,5
2G
7/2
2H
11/2
4F
9/2
Energy /eV
Inte
nsity (
norm
.)
Wavelength /nm
17
2 n
m
Germicidal efficiancy (DIN 5031-10): 57,3 %
YPO4:NdExc.: 160 nm
Em.: 200 nm
4f25d
1
4IJ
0
10
20
30
40
50
60
70
80
90
100
Reflecta
nce / %
BaS
O4
λmax(YPO4:Bi) = 241 nm
λmax(YPO4:Pr) = 235 nm
λmax(YPO4:Nd) = 193 nm
Y3+ site: CN = 8
Chosen converter material must be radiation hard
YPO4 as the host material
mineral: Xenotime
structure: Zircon type
crystal system: tetragonal
space group: I41/amd (#141)
unit cell
T. Jüstel, H. Nikol, J. Dirscherl, W. Busselt, US 6398970 B1
T. Jüstel, H. von Busch, G. Heussler, W. Mayr, US 7298077 B2
G.F. Gärtner, G. Greuel, T. Jüstel, W. Schiene, US 7687997 B2
T. Jüstel, J. Meyer, W. Mayr, US 7808170 B2
T. Jüstel, P. Huppertz, D.U. Wiechert, W. Mayr, H. von Busch, US 7855497 B2
G. Greuel, T. Jüstel. J.M. Kuc, US 9334442 B2
Prof. Dr. T. Jüstel, Münster University of Applied Sciences, Germany Slide 26
Germicidal efficacy of doped ortho-phosphate YPO4
Germicidal Action Curve (GAC):
Efficacy of deactivation of E. Coli (DIN 5031-10)
5. VUV to UV Converter Design
200 250 300 350 400 450 500
0,0
0,1
0,2
0,3
0,4
0,5
0,6
0,7
0,8
0,9
1,0
0,0
0,1
0,2
0,3
0,4
0,5
0,6
0,7
0,8
0,9
1,0
GAC
YPO4:Nd
Em
issio
n inte
nsity (
norm
.)
Spectral germicidal efficacy DIN 5031-10 (E.Coli)
Germ
icid
al effic
acy /a.u
.
Wavelength /nm
GAC-Eff (YPO4:Nd) = 57.3 %
200 250 300 350 400 450 500
0,0
0,1
0,2
0,3
0,4
0,5
0,6
0,7
0,8
0,9
1,0
0,0
0,1
0,2
0,3
0,4
0,5
0,6
0,7
0,8
0,9
1,0
GAC
YPO4:Bi
Em
issio
n Inensity (
norm
.)
Spectral germicidal efficacy DIN 5031-10 (E.Coli)
Germ
icid
al effic
acy /a.u
.
Wavelength /nm
GAC-Eff (YPO4:Bi) = 43.8 %
200 250 300 350 400 450 500
0,0
0,1
0,2
0,3
0,4
0,5
0,6
0,7
0,8
0,9
1,0
0,0
0,1
0,2
0,3
0,4
0,5
0,6
0,7
0,8
0,9
1,0
GAC
YPO4:Pr
Em
issio
n Inensity (
norm
.)
Spectral germicidal efficacy DIN 5031-10 (E.Coli)
Germ
icid
al effic
acy /a.u
.
Wavelength /nm
GAC-Eff (YPO4:Pr) = 60.6 %
𝐸𝑓𝑓𝐺𝐴𝐶(𝑃ℎ𝑜𝑠𝑝ℎ𝑜𝑟) = (𝐸𝑚𝑃ℎ𝑜𝑠𝑝ℎ𝑜𝑟× 𝐺𝐴𝐶)
𝐸𝑚𝑃ℎ𝑜𝑠𝑝ℎ𝑜𝑟
YPO4:Bi
YPO4:Pr
YPO4:Nd
Goal: Log-4 reduction
Prof. Dr. T. Jüstel, Münster University of Applied Sciences, Germany Slide 27
YPO4:Bi or YPO4:Pr comprising lamps
Goal: Degradation of sulfamethoxazol (antibiotic)
Source: A. Nietzsch, DLR
Source: N. Braun, GVB
Photolytical degradation by the use of a phosphor converted Xe excimer lamp
allows a reduction of the required dose by 95% compared to an amalgam lamp
6. Phosphor Converted Xe Excimer Lamps
Prof. Dr. T. Jüstel, Münster University of Applied Sciences, Germany Slide 28
H2O filled dive-in test stand for
Xe excimer co-axial lamps
Converter
screen
Operation
period
Relative radiation
intensity loss
YPO4:Bi 792 hours - 50 %
YPO4:Pr 792 hours - 60 %
YPO4:Nd 763 hours ~ -50 %
But: An YPO4:Bi lamp has reached its
rated end of life after just about 240
hours of operation if L70 is applied
6. Phosphor Converted Xe Excimer Lamps
Lifetime of Xe excimer lamp comprising YPO4:Bi or YPO4:Ln
Choice was based on
LnPO4 phosphors are stable in discharge lamps
Wide band gap (Eg ~ 8.8 eV) limits re-absorption
50 100 150 200 250 300 350 400 450 500 550 600 650 700
100
120
140
160
180
200
220
240
260
IUV-C
Lamp with YPO4:Bi
Inte
gra
ted U
V-C
In
tensity /
a.u
.
Run-time /h
0
-10
-20
-30
-40
-50
-60
-70
-80
Degradation Lamp with YPO4:Bi
De
gra
da
tion
/ %
L70
L70 @ ≈ 240 h
Prof. Dr. T. Jüstel, Münster University of Applied Sciences, Germany Slide 29
6. Phosphor Converted Xe Excimer Lamps
50 100 150 200 250 300 350 400 450 500 550 600 650 700
100
120
140
160
180
200
220
240
260
IUV-C
Lamp with YPO4:Bi
Inte
gra
ted U
V-C
In
tensity /
a.u
.
Run-time /h
0
-10
-20
-30
-40
-50
-60
-70
-80
Degradation Lamp with YPO4:Bi
De
gra
da
tion
/ %
L70
L70 @ ≈ 240 h 150 200 250 300 350 400 450 500 550 600 650 700 750 800
8,3 6,2 5,0 4,1 3,5 3,1 2,8 2,5 2,3 2,1 1,9 1,8 1,7 1,5
Energy /eV
Inte
nsity (
norm
.)
Wavelength /nm
Exc.: 160 nm
Em.: 233 nm
YPO4:Bi
YPO4:Bi aged
0
10
20
30
40
50
60
70
80
90
100
Reflecta
nce / %
BaS
O4
240 260 280 300 320 340 360 380
Lifetime of Xe excimer lamp comprising YPO4:Bi or YPO4:Ln
Lamp degradation due to several processes YPO4:Bi as-made and aged
(PL and reflection spectra)
Discharge related Phosphor related
XeO* formation Reduction of Bi3+ Bi2+, Bi+
Sputtering of central wire Degradation of ortho-phosphate host
(defects or phosphate reduction?)
Prof. Dr. T. Jüstel, Münster University of Applied Sciences, Germany Slide 30
150 200 250 300 350 400 450 500 550 600 650 700 750 800
8,3 6,2 5,0 4,1 3,5 3,1 2,8 2,5 2,3 2,1 1,9 1,8 1,7 1,5
Energy /eV
Inte
nsity (
no
rm.)
Wavelength /nm
Exc.: 160 nm
Em.: 235 nm
YPO4:Pr
YPO4:Pr aged
0
10
20
30
40
50
60
70
80
90
100
Re
fle
cta
nce
/ %
Ba
SO
4
YPO4:Pr3+
new
absorption
due to host
degradation
150 200 250 300 350 400 450 500 550 600 650 700 750 800
8,3 6,2 5,0 4,1 3,5 3,1 2,8 2,5 2,3 2,1 1,9 1,8 1,7 1,5
Energy /eV
Inte
nsity (
no
rm.)
Wavelength /nm
Exc.: 160 nm
Em.: 233 nm
YPO4:Bi
YPO4:Bi aged
0
10
20
30
40
50
60
70
80
90
100
Re
fle
cta
nce
/ %
Ba
SO
4240 260 280 300 320 340 360 380
YPO4:Bi3+
new
absorption
by Bi+/ Bi2+
200 250 300 350 400 450 500 550 600 650 700 750 800
6,2 5,0 4,1 3,5 3,1 2,8 2,5 2,3 2,1 1,9 1,8 1,7 1,5
Energy /eV
Inte
nsity (
norm
.)
Wavelength /nm
Exc.: 160 nm
Em.: 233 nm
YPO4 aged
0
10
20
30
40
50
60
70
80
90
100
YPO4
Reflecta
nce / %
BaS
O4
undoped YPO4
Degradation of YPO4:Bi, YPO4:Pr, and undoped YPO4
6. Phosphor Converted Xe Excimer Lamps
Prof. Dr. T. Jüstel, Münster University of Applied Sciences, Germany Slide 31
200 250 300 350 400 450 500 550 600 650 700 750 800
6,2 5,0 4,1 3,5 3,1 2,8 2,5 2,3 2,1 1,9 1,8 1,7 1,5
Energy /eV
Inte
nsity (
no
rm.)
Wavelength /nm
Exc.: 160 nm
Em.: 233 nm
YPO4 aged
0
10
20
30
40
50
60
70
80
90
100
YPO4
Re
fle
cta
nce
/ %
Ba
SO
4
YPO4
as-made
YPO4
aged
YPO4
aged + 365 nm
200 250 300 350 400 450 500 550 600 650 700 750 800
6,2 5,0 4,1 3,5 3,1 2,8 2,5 2,3 2,1 1,9 1,8 1,7 1,5
77K
100K
123K
150K
175K
200K
225K
250K
Energy /eV
Inte
nsi
ty /a.u
.
Wavelength /nm
275K
300K
325K
350K
375K
400K
Ex.: 350
Em.: 750YPO
4 aged @
425K
450K
475K
500K
0
10
20
30
40
50
60
70
80
90
100
Refle
ctance
/ %
BaS
O4
Temperature dependent spectroscopy on aged YPO4 samples
Aged undoped YPO4
shows intense red
photoluminescence
Nature of luminescence process?
6. Phosphor Converted Xe Excimer Lamps
Prof. Dr. T. Jüstel, Münster University of Applied Sciences, Germany Slide 32
6. Phosphor Converted Xe Excimer LampsBi3+ doping Pr3+ doping
200 250 300 350 400 450 500 550 600 650 700 750 800
6,2 5,0 4,1 3,5 3,1 2,8 2,5 2,3 2,1 1,9 1,8 1,7 1,5
77K
100K
125K
150K
175K
200K
225K
Energy /eV
Inte
nsi
ty (
norm
.)
Wavelength /nm
250K
275K
300K
325K
350K
375K
400K
425K
450K
475K
500KYPO
4:Bi aged
Exc.: 340nm
Em.: 700nm
0
10
20
30
40
50
60
70
80
90
100
Refle
ctance
/ %
BaS
O4
200 250 300 350 400 450 500 550 600 650 700 750 800
6,2 5,0 4,1 3,5 3,1 2,8 2,5 2,3 2,1 1,9 1,8 1,7 1,5
77K
100K
123K
150K
175K
200K
225K
250K
Energy /eV
Inte
nsi
ty /
a.u
.
Wavelength /nm
275K
300K
325K
350K
375K
400K
Ex.: 350
Em.: 750YPO
4 aged @
425K
450K
475K
500K
0
10
20
30
40
50
60
70
80
90
100
Re
flect
ance
/ %
Ba
SO
4
Gd3+ doping
YPO4 host
250 300 350 400 450 500 550 600 650 700 750 800
5,0 4,1 3,5 3,1 2,8 2,5 2,3 2,1 1,9 1,8 1,7 1,5
Energy /eV
Inte
nsity (
norm
.)
Wavelength /nm
17
2 n
m
Exc.: 348 nm
Em.: 735 nmYPO
4:Pr aged @
80 K
100 K
120 K
140 K
160 K
180 K
200 K
220 K
240 K
260 K
280 K
300 K
320 K
340 K
360 K
380 K
400 K
420 K
440 K
460 K
480 K
500 K
0
10
20
30
40
50
60
70
80
90
100
Reflecta
nce / %
BaS
O4
200 250 300 350 400 450 500 550 600 650 700 750 800
6,2 5,0 4,1 3,5 3,1 2,8 2,5 2,3 2,1 1,9 1,8 1,7 1,5
77K
100K
125K
150K
175K
200K
225K
250K
275K
Energy /eV
Inte
nsi
ty (
no
rm.)
Wavelength /nm
Exc.: 345 nm
Em.: 750 nmYPO
4:Gd
300K
325K
350K
375K
400K
425K
450K
475K
500K
0
10
20
30
40
50
60
70
80
90
100
Re
flect
ance
/ %
Ba
SO
4
Luminescence process:
• Independent of type of
dopant ion
• Similar PL found for
aged LuPO4 and LaPO4
PL related to phosphate
YPO4:Gd YPO4:Gd
aged
YPO4:Gd
aged +
365 nm
Prof. Dr. T. Jüstel, Münster University of Applied Sciences, Germany Slide 33
6. Phosphor Converted Xe Excimer Lamps
Further analytics on degraded LnPO4 (Ln = Y, La, Gd, Lu)
• XRD and 31P-NMR No phase transitions or impurity phase formation
• Photoluminescence spectroscopy Spectral features characteristic for
ns2 ns1np1 luminescence, as already known for As3+, Sb3+, and Bi3+
• Decay curve main component 1/e = 5 ms PL of s2-ion with a small
spin-orbit (S.-O.) coupling, which increases with atomic number!
P+V P+III
[Ne]3s0 [Ne]3s2
Reduction of P5+ by hot e- and Xe+∙
impingement due to intimate contact
to barrier discharge
P+VO43- + Xe+ + e- P+IIIO3
3- + XeO
0 5 10 15 20 25 30 35 4010
0
101
102
103
104
Inte
nsity
/cou
nts
time / ms
YPO4 recovered
Fit (2nd.
exponential)
Exc.: 330 nm
Em.: 770 nm
1 = 1378.24 s ± 56.70 s
2 = 5007.80 s ± 25.91 s
1= 11.31%
2 = 88.63%
= 1.114
+
-
P3+
As3+
Sb3+
Bi3+
+
-
-
+
Prof. Dr. T. Jüstel, Münster University of Applied Sciences, Germany Slide 34
6. Phosphor Converted Xe Excimer Lamps
200 250 300 350 400 450 500 550 600 650 700 750 800
6,2 5,0 4,1 3,5 3,1 2,8 2,5 2,3 2,1 1,9 1,8 1,7 1,5
Energy /eV
Inte
nsity /
arb
. un
its
Wavelength /nm
80 K
100 K
120 K
140 K
160 K
180 K
200 K
220 K
240 K
260 K
280 K
300 K
320 K
340 K
360 K
380 K
400 K
420 K
440 K
460 K
480 K
500 K
0,0
0,1
0,2
0,3
0,4
0,5
0,6
0,7
0,8
0,9
1,0
Reflection @ RT
Re
fle
cta
nce
/ %
Ba
SO
4
C AB A
C AB
1S0
3P0
3P1
3P2
1P1
A
1S0
3P0
3P1
3P2
1P1
Exc. Em.
x
Simplified energy level
diagram of an ns2 ion
Photoluminescence of degraded LnPO4 (Ln = Y, La, Gd, Lu)
Conclusions:
• Formation of LnPO4:P3+
• First known example of P3+ [Ne]3s2 to [Ne]3s13p1 photoluminescenceM. Broxtermann, R. Poettgen, T. Jüstel, et al., J. Luminescence, publication in preparation
Prof. Dr. T. Jüstel, Münster University of Applied Sciences, Germany Slide 35
6. Phosphor Converted Xe Excimer Lamps
Improvement of stability of LnPO4:M (Ln = Y, La, Gd, Lu; M = Pr, Nd, Bi)
Approach: Particle coating with Al2O3 (Eg ~ 7.5 eV) to reduce interaction with
Xe discharge and to absorb radiation from discharge below 160 nm
YPO4:Bi
Al2O3
172 nm
241 nm
0 60 120 180 240 300 360
4
5
6
7
pH
pH
Time /min.
Al(OH)3 precipitation by h induced NaN
3 cleavage
8
10
12
14
16
18
20
V(Reaktor) = 0.85 L
m(YPO4:Bi) = 0 g
conc.(NaN3) = 7,65 g/L (6,5g)
c(Al2(SO4)
3x16H
2O) = 2 g/L (1,7 g)
Temperature
Te
mp
era
ture
/°C
147 nm
M. Broxtermann, T. Jüstel, Mat. Res. Bull. 80 (2016) 249
Prof. Dr. T. Jüstel, Münster University of Applied Sciences, Germany Slide 36
6. Phosphor Converted Xe Excimer Lamps
Improvement of stability of LnPO4 (Ln = Y, La, Gd, Lu)
Al2O3 reduces efficacy upon 160 nm,
but hardly upon 172 nm excitation
non coated 1 wt-% Al2O3
2 wt-% Al2O3 4 wt-% Al2O3
150 200 250 300 350 400 450 500 550 600
YPO4:Bi
4 wt% Al2O
3
2 wt% Al2O
3
1 wt% Al2O
3
0 wt% Al2O
3
Inte
nsity (
no
rm.)
Wavelength /nm
Em.: 260 nm // Exc.: 160 nm
0
10
20
30
40
50
60
70
80
90
100R
efle
cta
nce
/ %
Ba
SO
4
220 230 240 250 260 2700,0
0,2
0,4
0,6
0,8
1,0
Wavelength /nm
Inte
nsity (
no
rm.)
2 3 4 5 6 7 8 9 10-200
-150
-100
-50
0
50
100
150
200
2 3 4 5 6 7 8 9 10
neat YPO4
1 wt.% coated
2 wt.% coated
4 wt.% coated
Al2O
3
Ze
ta P
ote
ntial /m
V
pH
2,7 4,5 5,0 6,4 8.1
Prof. Dr. T. Jüstel, Münster University of Applied Sciences, Germany Slide 37
6. Phosphor Converted Xe Excimer Lamps
Lifetime of Xe excimer lamp comprising Al2O3 coated YPO4:Bi particles
50 100 150 200 250 300 350 400 450 500 550 600 650 700
100
120
140
160
180
200
220
240
260
UV-C intensity with YPO4:Bi, neat
UV-C intensity with YPO4:Bi, Al2O
3 coated (4m%, UV-R, 1400°C)
Inte
gra
ted U
V-C
inte
nsity (
norm
by IR
)
Operation time /h
0
-10
-20
-30
-40
-50
-60
-70
-80
Degradation withYPO4:Bi, neat
Degradation with YPO4:Bi, Al2O
3 coated (4m%, UV-R, 1400°C)
Degra
dation / %
Coating type Lamp code Operation time / h 72 216 336 480 700
none 837 loss / % 14.17 29 37.99 55.76 52.21
Al2O3 2 wt-%, urea 838 loss / % 20.29 41.92 48.58 50.06 43.43
Al2O3 4 wt-%, urea 827 loss / % n. a. 22.47 24.04 30.37 32.58
Al2O3 2 wt-%, UV-R 828 loss / % 12.40 24.91 33.81 32.35 40.23
Al2O3 4 wt-%, UV-R 829 loss / % 12.61 26.95 24.94 32.72 42.01
Al2O3 4 wt-%, UV-R, 1400 °C 830 loss / % 5.25 16.28 19.86 24.64 28.44
Optimal particle coating process
• Al2(SO4)3 in water + NaN3
• UV reactor (Hg high-pressure lamp)
• 4 wt-% Al2O3
• 1400 °C post annealing
Results so far
• Factor 2 - 3 less degradation
• Almost no loss of initial efficiency
Prof. Dr. T. Jüstel, Münster University of Applied Sciences, Germany Slide 38
YPO4:Pr and LuPO4:Pr as 235 nm UV-C emitting nanoparticle scintillators
YPO4:Pr (30 nm)
LuPO4:Pr (5 nm)
100 200 300 400 500 600 700 800 0.0
0.2
0.4
0.6
0.8
1.0
YPO4:Pr3+
(1%)
Emissionsspektrum Anregungsspektrum
Probe EDTA 2
Re
lative
In
tensitä
t
Wellenlänge [nm]
4 f2 5 d
14 f
1
5 d14 f
1
3H4
7. Spin-off: Nanoscale UV Scintillators
°2Theta
10 20 30 40 50 60
Counts
0
25
100
LuPO4:Pr(1%)
EDTA 16
Prof. Dr. T. Jüstel, Münster University of Applied Sciences, Germany Slide 39Friday Afternoon
Idea: Conversion of x-rays to UV-C radiation by nanoscale particles to
improve radiation therapy of cancer
Radiation therapy is a well established
cancer treatment and applied all over
the world, even though it has tremendous
side effects, such as hair loss, diarrhea, …
“UV Nanophors” would result in
• lower radiation dose
• fewer or none side effects
• lower treatment price
• shorter treatment periods
7. Spin-off: Nanoscale UV Scintillators
T. Jüstel, C. Feldmann, Philips Patent EP03104756, WO2005058360
Image by
S. Espinoza
Prof. Dr. T. Jüstel, Münster University of Applied Sciences, Germany Slide 40
Challenge: Provide UV-C scintillator
which meet the following requirements
• High density
• Large GAC overlap
• Diameter: 50 - 150 nm
• Narrow PSD
• Homogeneous morphology
• Redispersibility
• Mainly UV-C emission
• Efficient CL and RL
• Suitable PZC
• Biocompatible host
• Low toxicity
• Stability in water to enable
core-shell structure with linker
7. Spin-off: Nanoscale UV Scintillators
Core material
Density
[g/cm3]
Lu2O3 9.4
LuLaO3 8.2
Lu2O2S 8.9
Lu2SiO5 7.4
LuPO4 6.53
Lu2Si2O7 6.2
Lu3Al5O12 6.7
LuAlO3 8.4
LuBO3 6.9
Image by
S. Espinoza
Prof. Dr. T. Jüstel, Münster University of Applied Sciences, Germany Slide 41
Material λmax.(Em.) /nm GAC-Efficacy /%
(Y,Lu)PO4:Nd 193 57.3*
CaSO4:Pr,Li 218 68,2
LaPO4:Pr 225 68.9
(Y,Lu)PO4:Pr 235 60.6
(Y,Lu)PO4:Bi 241 43.8 – 50.7
YAlO3:Pr 245 40.6
La2Si2O7:Pr 247 33.4
CaLi2SiO4:Pr 253 44.0
CaMgSi2O6:Pr,Li 260 n. a.
YBO3:Pr 265 45.9
Lu2Si2O7:Pr 266 48.1
Y2SiO5:Pr 270 22.3
BaZrSi3O9 275 47.9
Lu2SiO5 277 15.9
Lu3Al5O12:Pr 310 2.3
Lu3Al5O12:Gd 311 ~ 0
Y3Al5O12:Gd 311 ~ 0
LaMgAl11O19:Gd 311 ~ 0
Y3Al5O12:Pr 320 ~ 0
Material λmax.(Em.) /nm GAC-Efficacy /%
LaPO4:Ce 320 ~ 0
Lu3Al5O12:Tm 345 ~ 0
Y3Al5O12:Tm 345 ~ 0
YPO4:Ce 335, 355 ~ 0
BaSi2O5:Pb 350 ~ 0
7. Spin-off: Nanoscale UV Scintillators
Emission peaks and GAC overlap of selected UV-C scintillators
Prof. Dr. T. Jüstel, Münster University of Applied Sciences, Germany Slide 42
7. Spin-off: Nanoscale UV Scintillators
GAC overlap and density of selected UV-C scintillators
LaPO4 LuPO4
Chosen materials
Prof. Dr. T. Jüstel, Münster University of Applied Sciences, Germany Slide 43
LuPO4
Sedimentation Nucleation (Modified)
Suspension
• A solution of NaH2PO4 (pH 12) is added dropwise to the
second solution of LuCl3 and Pr(NO3)3 dissolved in H2O.
• The precipitate is separated by a centrifuge and washed
with distilled H2O several times to neutral pH value.
• Afterwards, the precipitate is annealed for 2 h at 1000
°C in a reducing atmosphere (CO).
• Lu2O3 and Pr6O11 are suspended in H2O.
• H3PO4 is added to the suspension and mixed for 24 h.
• The precipitate is filtered and washed with distilled H2O
several times to neutral pH value.
• Afterwards, the precipitate is annealed for 4 h at 1000 °C
under CO atmosphere and using
2 wt-% LiF.
Average d50 = 0.1 µm Average d50 = 5.7 µm
7. Spin-off: Nanoscale UV Scintillators
From micro to nanoscale particles (bottom-up approach)
Image by
Sara Espinoza
Prof. Dr. T. Jüstel, Münster University of Applied Sciences, Germany Slide 44
7. Spin-off: Nanoscale UV Scintillators
Reproducible synthesis of pure and highly crystalline LuPO4:Pr3+ 100 nm particle activated by 0.1 to 3% Pr3+
PSD of nanoscale LuPO4:Pr(0.0 - 3.0 atom-%) particles
0,01 0,1 1 10 100
0
2
4
6
8
10
12
14
q [
%]
Particle Diameter [m]
0
10
20
30
40
50
60
70
80
90
100
LuPO4
HMS-2017-PM-AU-025
Cu
mu
lativ
e fr
actio
n u
nd
er s
ize [v
ol-%
]
D10= 0.07 µm
D50= 0.1 µm
D90= 0.6 µm
= 1.7 µm
0,01 0,1 1 10 100
0
2
4
6
8
10
12
14
q [
%]
Particle Diameter [m]
0
10
20
30
40
50
60
70
80
90
100
LuPO4:Pr3+
(0.1%)
HMS-2017-PM-AU-024
Cu
mu
lativ
e fr
actio
n u
nd
er s
ize [v
ol-%
]
D10= 0.1 µm
D50= 0.1 µm
D90= 0.4 µm
= 0.5 µm
0,01 0,1 1 10 100
0
2
4
6
8
10
12
14
q [
%]
Particle Diameter [m]
0
10
20
30
40
50
60
70
80
90
100
LuPO4:Pr3+
(0.25%)
HMS-2017-PM-AU-026
Cu
mu
lativ
e fr
actio
n u
nd
er s
ize [v
ol-%
]
D10= 0.07 µm
D50= 0.1 µm
D90= 0.7 µm
= 0.8 µm
0,01 0,1 1 10 100
0
2
4
6
8
10
12
14
q [
%]
Particle Diameter [m]
0
10
20
30
40
50
60
70
80
90
100
LuPO4:Pr3+
(0.5%)
HMS-2017-PM-AU-027
Cu
mu
lativ
e fr
actio
n u
nd
er s
ize [v
ol-%
]
D10= 0.08 µm
D50= 0.1 µm
D90= 0.3 µm
= 0.2 µm
0,01 0,1 1 10 100
0
2
4
6
8
10
12
14
q [
%]
Particle Diameter [m]
0
10
20
30
40
50
60
70
80
90
100
LuPO4:Pr3+
(1%)
HMS-2017-PM-AU-028
Cu
mu
lativ
e fr
actio
n u
nd
er s
ize [v
ol-%
]
D10= 0.07 µm
D50= 0.1 µm
D90= 0.3 µm
= 0.5 µm
0,01 0,1 1 10 100
0
2
4
6
8
10
12
14
q [
%]
Particle Diameter [m]
0
10
20
30
40
50
60
70
80
90
100
LuPO4:Pr3+
(2%)
HMS-2017-PM-AU-031
Cu
mu
lativ
e fr
actio
n u
nd
er s
ize [v
ol-%
]
D10= 0.08 µm
D50= 0.1 µm
D90= 0.6 µm
= 0.5 µm
0,01 0,1 1 10 100
0
2
4
6
8
10
12
14
q [
%]
Particle Diameter [m]
0
10
20
30
40
50
60
70
80
90
100
LuPO4:Pr3+
(3%)
HMS-2017-PM-AU-032
Cu
mu
lativ
e fr
actio
n u
nd
er s
ize [v
ol-%
]
D10= 0.08 µm
D50= 0.1 µm
D90= 0.4 µm
= 0.4 µm
Results from S. Espinoza, H. Jenneboer, H. Kaetker, and A. Uckelmann
Prof. Dr. T. Jüstel, Münster University of Applied Sciences, Germany Slide 45
7. Spin-off: Nanoscale UV Scintillators
Density [g/cm3] 6.5 4.2
Main peak [nm] 235 225
Luminescence 4f-5d and 4f-4f mainly 4f-5d
GAC overlap [%] 61 69
200 250 300 350 400 450 500 550 600 650 700 750 8000,00
2,50x10-2
5,00x10-2
7,50x10-2
1,00x10-1
Tb3+
Tb3+
Tb3+
Pr3+
: [Xe]4f2- [Xe]4f
2
Pr3+
: [Xe]4f15d
1- [Xe]4f
2
Tb3+
LuPO4
LuPO4:Pr
3+ 0.1%
LuPO4:Pr
3+ 0.25%
LuPO4:Pr
3+ 0.5%
LuPO4:Pr
3+ 1%
LuPO4:Pr
3+ 2%
LuPO4:Pr
3+ 3%
Inte
nsi
ty (
a.u
.)
Wavelength (nm)
6 5 4 3 2 1,54
Energy (eV)
ex= X-ray
50 kV; 2 mA
Tungsten Target
5 Repeats
Radioluminescence of LuPO4:Pr and LaPO4:Pr 100 nm particles
LuPO4:Pr LaPO4:Pr
200 250 300 350 400 450 500 550 600 650 700 750 8000,00
3,50x106
7,00x106
1,05x107
1,40x107
Pr3+
:[Xe]4f2- [Xe]4f
2
Pr3+
: [Xe]4f15d
1- [Xe]4f
2 YPO
4:Bi
3+ UV-C 13/03 (4.2 m)
HMS-2017-AU-SS-103: LaPO4:Pr
3+ (0.1%)
HMS-2017-AU-SS-104: LaPO4:Pr
3+ (0.25%)
HMS-2017-AU-SS-105: LuPO4:Pr
3+ (0.5%)
HMS-2017-AU-SS-106: LaPO4:Pr
3+ (1%)
Inte
nsi
ty (
a.u.)
Wavelength (nm)
6 5,5 5 4,5 4 3 2,5 2 1,54
Energy (eV)
ex= X-ray
50 kV; 2 mA
Tungsten Target
5 Repeats
Prof. Dr. T. Jüstel, Münster University of Applied Sciences, Germany Slide 46
7. Spin-off: Nanoscale UV Scintillators
First results on cancer cell lines (source: HMS Boston, Dr. M. Purschke)
Combined treatment causes an increased cell inactivation of 65 to 95%.
Combined treatment of cells with LuPO4:Pr3+ and 2 Gy is equivalent to 4 Gy alone
C o n tro lN P s
4 Gy X
-ra y
4 Gy X
-ra y + N
P s
1 0 0 J m
-2 UV C
0
1
2
3
4
5
6
7
1 0
2 0
Ab
so
rb
an
ce
, a
rb
.un
it
a b s = 4 5 0 n m
Cyclobutane pyrimidine dimer
assay as a proof of concept
0 .0 0 .5 1 .0 2 .5 5 .0 7 .5 0 .0 0 .5 1 .0 2 .5 5 .0 7 .51
1 0
1 0 0
C o n c e n tra tio n o f N P s , m g m l-1
Su
rv
ivin
g f
ra
cti
on
, %
0 G y 2 G y
* *
*
*
**
*
Colony formation assay
14 days after irradiation
Prof. Dr. T. Jüstel, Münster University of Applied Sciences, Germany Slide 47
8. Summary
180 200 220 240 260 280 3000,0
1,5x103
3,0x103
4,5x103
6,0x103
Nd3+
: [Xe]4f25d
1- [Xe]4f
3
Pr3+
: [Xe]4f15d
1- [Xe]4f
2
YPO4:Nd
3+ TL0138
LuPO4:Pr
3+ (3%) d
50 = 100 nm
LuPO4:Pr
3+ (3%) d
50 = 13 m
Inte
nsi
ty (
a.u.)
Wavelength (nm)
7 6 5 4,13
Energy (eV)
ex=160 nm
3 Repeats
UV emitting (nanoscale) materials
Fluorescent Xe Excimer discharge lamps
• Tailored emission spectra possible by VUV UV converter:
(Y,Lu)PO4:Nd, LaPO4:Pr, (Y,Lu)PO4:Pr, YBO3:Pr, BaZrSi3O9, …
• Lamp lifetime limited to ~1000 h yet
• Degradation mechanism clarified
• Improvement of stability of converter by photochemically
deposited Al2O3 particle coatings
• Many application areas, such as disinfection, purification,
photochemistry, NO3- removal, food processing, …
Nanoscale UV emitting phosphors
• Excitation by x- or cathode-rays
• Local emission of harmful UV-C or VUV radiation
• Use for surface disinfection or therapeutic purposes
• Development of quantitative VUV/x-ray to UV-C spectroscopy
Prof. Dr. T. Jüstel, Münster University of Applied Sciences, Germany Slide 48
UV emitting (Al,Ga)N LEDs and laser diodes
• Spectral range: 220 – 360 nm
• DUV-LED → DUV laser diodes: Challenging!
• Problems: Spectral consistency, efficiency,
radiation out-coupling, mass production,
encapsulation, …..
Fluorescent Xe excimer discharge lamps
• Spectral range: 190 – 700 nm
• Discharge – converter interaction determines yield
& lifetime
• Advantages: Hg-free, fast switchable, high form
factor, temperature independent
• Problems: Driver eff., lifetime, market access, but
UNEP proposed Hg ban rom 2020 onwards …..
8. Outlook
Prof. Dr. T. Jüstel, Münster University of Applied Sciences, Germany Slide 49
UV emitting nanoscale core-shell particles for biomedical applications
8. Outlook
Diagnostics
Imaging
Therapy
Delivery
Combination of
these applications,
e.g. for magneto-
optical therapy
GdPO4 (core) +
LuPO4:Pr (shell)
Her, S., Jaffray, D.A. and Allen, C., Gold nanoparticles for applications in cancer radiotherapy,
Mechanisms and recent advancements, Advanced drug delivery reviews, 109 (2017) 84
Prof. Dr. T. Jüstel, Münster University of Applied Sciences, Germany Slide 50
Acknowledgement
• Research Group “Tailored Optical Materials“ Mike Broxtermann, Jan-Niklas Keil, and Sara Espinoza for their dedicated research work
• HMS Boston, MA, USADr. M. Purschke for fruitful discussions
• University of Tübingen, GermanyProf. H.-J. Meyer for fruitful discussions
• Vilnius University, LithuaniaProf. A. Kareiva for exchange of students
• Universiteit Utrecht, The NetherlandsProf. A. Meijerink for fruitful discussions
• BMBF, BMWI, Merck KGaA Darmstadt, Philips Lighting Eindhoven, Berger GmbH, GVB Solutions in Quartz, and Xylem Herford for generous financial support