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BERKELEY•DAVIS•IRVINE•LOS ANGELES•MERCED•RIVERSIDE•SAN DIEGO•SAN FRANCISCO•SANTA BARBARA•SANTA CRUZ
Department of ChemistryUNIVERSITY OF CALIFORNIA, IRVINE
Vishnu Vardhan Krishnamachari
Heterodyne CARS imaging:First results
Group SeminarJune 2, 2006
Vishnu Krishnamachari Group Seminar: June 2, 2006
Contents
Raman
CARS
HeterodyneCARS
Setup
Results
BERKELEY•DAVIS•IRVINE•LOS ANGELES•MERCED•RIVERSIDE•SAN DIEGO•SAN FRANCISCO•SANTA BARBARA•SANTA CRUZ
Department of ChemistryUNIVERSITY OF CALIFORNIA, IRVINE
Contents
CARS is not Raman!
Heterodyne CARS
Experimental setup
DMSO-Glass Experiment
Contents
Vishnu Krishnamachari Group Seminar: June 2, 2006
Contents
Raman
CARS
HeterodyneCARS
Setup
Results
BERKELEY•DAVIS•IRVINE•LOS ANGELES•MERCED•RIVERSIDE•SAN DIEGO•SAN FRANCISCO•SANTA BARBARA•SANTA CRUZ
Department of ChemistryUNIVERSITY OF CALIFORNIA, IRVINE
CARS is not Raman!
Frequency dependence of third-order non-linearsusceptibility around a Raman transitionRaman
Vishnu Krishnamachari Group Seminar: June 2, 2006
Contents
Raman
CARS
HeterodyneCARS
Setup
Results
BERKELEY•DAVIS•IRVINE•LOS ANGELES•MERCED•RIVERSIDE•SAN DIEGO•SAN FRANCISCO•SANTA BARBARA•SANTA CRUZ
Department of ChemistryUNIVERSITY OF CALIFORNIA, IRVINE
CARS is not Raman!
Spontaneous Raman emission intensityRaman
Vishnu Krishnamachari Group Seminar: June 2, 2006
Contents
Raman
CARS
HeterodyneCARS
Setup
Results
BERKELEY•DAVIS•IRVINE•LOS ANGELES•MERCED•RIVERSIDE•SAN DIEGO•SAN FRANCISCO•SANTA BARBARA•SANTA CRUZ
Department of ChemistryUNIVERSITY OF CALIFORNIA, IRVINE
CARS is not Raman!
CARS intensity : Single peak
CARS
Vishnu Krishnamachari Group Seminar: June 2, 2006
Contents
Raman
CARS
HeterodyneCARS
Setup
Results
BERKELEY•DAVIS•IRVINE•LOS ANGELES•MERCED•RIVERSIDE•SAN DIEGO•SAN FRANCISCO•SANTA BARBARA•SANTA CRUZ
Department of ChemistryUNIVERSITY OF CALIFORNIA, IRVINE
CARS is not Raman!
CARS intensity : Double peak
CARS
Vishnu Krishnamachari Group Seminar: June 2, 2006
Contents
Raman
CARS
HeterodyneCARS
Setup
Results
BERKELEY•DAVIS•IRVINE•LOS ANGELES•MERCED•RIVERSIDE•SAN DIEGO•SAN FRANCISCO•SANTA BARBARA•SANTA CRUZ
Department of ChemistryUNIVERSITY OF CALIFORNIA, IRVINE
CARS is not Raman!
CARS intensity
Non-resonant and resonant signals interfere
Difficult to analyze the spectrum
Huge background => Poor SNR & sensitivity
CARS intensity is not proportional to the concentration
CARS
Vishnu Krishnamachari Group Seminar: June 2, 2006
Contents
Raman
CARS
HeterodyneCARS
Setup
Results
BERKELEY•DAVIS•IRVINE•LOS ANGELES•MERCED•RIVERSIDE•SAN DIEGO•SAN FRANCISCO•SANTA BARBARA•SANTA CRUZ
Department of ChemistryUNIVERSITY OF CALIFORNIA, IRVINE
Heterodyne CARS
Heterodyne detection:Detection of the desired signal by mixing it with a“known” or “well-characterized” signal.
HeterodyneCARS
Vishnu Krishnamachari Group Seminar: June 2, 2006
Contents
Raman
CARS
HeterodyneCARS
Setup
Results
BERKELEY•DAVIS•IRVINE•LOS ANGELES•MERCED•RIVERSIDE•SAN DIEGO•SAN FRANCISCO•SANTA BARBARA•SANTA CRUZ
Department of ChemistryUNIVERSITY OF CALIFORNIA, IRVINE
Heterodyne CARS
ωCARSωlo
Detector
• Δφ = π/2 ⇒ Ιout∝ Im{χ(3)}
∝ Conc • Δφ = 0 ⇒ Ιout∝ Re{χ(3)}
HeterodyneCARS
Vishnu Krishnamachari Group Seminar: June 2, 2006
Contents
Raman
CARS
HeterodyneCARS
Setup
Results
BERKELEY•DAVIS•IRVINE•LOS ANGELES•MERCED•RIVERSIDE•SAN DIEGO•SAN FRANCISCO•SANTA BARBARA•SANTA CRUZ
Department of ChemistryUNIVERSITY OF CALIFORNIA, IRVINE
Experimental Setup
Setup
Vishnu Krishnamachari Group Seminar: June 2, 2006
Contents
Raman
CARS
HeterodyneCARS
Setup
Results
BERKELEY•DAVIS•IRVINE•LOS ANGELES•MERCED•RIVERSIDE•SAN DIEGO•SAN FRANCISCO•SANTA BARBARA•SANTA CRUZ
Department of ChemistryUNIVERSITY OF CALIFORNIA, IRVINE
Experimental Setup
Setup
Vishnu Krishnamachari Group Seminar: June 2, 2006
Contents
Raman
CARS
HeterodyneCARS
Setup
Results
BERKELEY•DAVIS•IRVINE•LOS ANGELES•MERCED•RIVERSIDE•SAN DIEGO•SAN FRANCISCO•SANTA BARBARA•SANTA CRUZ
Department of ChemistryUNIVERSITY OF CALIFORNIA, IRVINE
DMSO Interference
X
Y
X0
Interference between local oscillator and CARS signal
Results
Vishnu Krishnamachari Group Seminar: June 2, 2006
Contents
Raman
CARS
HeterodyneCARS
Setup
Results
BERKELEY•DAVIS•IRVINE•LOS ANGELES•MERCED•RIVERSIDE•SAN DIEGO•SAN FRANCISCO•SANTA BARBARA•SANTA CRUZ
Department of ChemistryUNIVERSITY OF CALIFORNIA, IRVINE
DMSO Interference
Time
X0
Interference between local oscillator and CARS signal
Results
Vishnu Krishnamachari Group Seminar: June 2, 2006
Contents
Raman
CARS
HeterodyneCARS
Setup
Results
BERKELEY•DAVIS•IRVINE•LOS ANGELES•MERCED•RIVERSIDE•SAN DIEGO•SAN FRANCISCO•SANTA BARBARA•SANTA CRUZ
Department of ChemistryUNIVERSITY OF CALIFORNIA, IRVINE
DMSO-Glass Experiment
Glass DMSO
+ local oscillator
t
X0
Simultaneous observation of two heterodyne signals
Results
Vishnu Krishnamachari Group Seminar: June 2, 2006
Contents
Raman
CARS
HeterodyneCARS
Setup
Results
BERKELEY•DAVIS•IRVINE•LOS ANGELES•MERCED•RIVERSIDE•SAN DIEGO•SAN FRANCISCO•SANTA BARBARA•SANTA CRUZ
Department of ChemistryUNIVERSITY OF CALIFORNIA, IRVINE
DMSO-Glass Experiment
Amplitude of oscillation
Phase difference
Results
Vishnu Krishnamachari Group Seminar: June 2, 2006
Contents
Raman
CARS
HeterodyneCARS
Setup
Results
BERKELEY•DAVIS•IRVINE•LOS ANGELES•MERCED•RIVERSIDE•SAN DIEGO•SAN FRANCISCO•SANTA BARBARA•SANTA CRUZ
Department of ChemistryUNIVERSITY OF CALIFORNIA, IRVINE
DMSO-Glass Experiment
Results
Vishnu Krishnamachari Group Seminar: June 2, 2006
Contents
Raman
CARS
HeterodyneCARS
Setup
Results
BERKELEY•DAVIS•IRVINE•LOS ANGELES•MERCED•RIVERSIDE•SAN DIEGO•SAN FRANCISCO•SANTA BARBARA•SANTA CRUZ
Department of ChemistryUNIVERSITY OF CALIFORNIA, IRVINE
DMSO-Glass Experiment
Results
Vishnu Krishnamachari Group Seminar: June 2, 2006
Contents
Raman
CARS
HeterodyneCARS
Setup
Results
BERKELEY•DAVIS•IRVINE•LOS ANGELES•MERCED•RIVERSIDE•SAN DIEGO•SAN FRANCISCO•SANTA BARBARA•SANTA CRUZ
Department of ChemistryUNIVERSITY OF CALIFORNIA, IRVINE
DMSO-Glass Experiment
Discrepancies
Results
Vishnu Krishnamachari Group Seminar: June 2, 2006
Contents
Raman
CARS
HeterodyneCARS
Setup
Results
BERKELEY•DAVIS•IRVINE•LOS ANGELES•MERCED•RIVERSIDE•SAN DIEGO•SAN FRANCISCO•SANTA BARBARA•SANTA CRUZ
Department of ChemistryUNIVERSITY OF CALIFORNIA, IRVINE
Conclusion
Raman versus CARS
Non-resonant background and its role
CARS intensity is not proportional to conc.
CARS Heterodyne setup
Experiments with DMSO + Glass