J. Phys. Chem. Lett., 2010, 1, 215-218
Feb 03, 2016
J. Phys. Chem. Lett., 2010, 1, 215-218
Introduction
Electron transfer (ET) processes and charge transfer (CT) states are involved in photosynthesis utilized in opto-electronic devices
Electron donor acceptor (DA) molecules are useful for studying fundamental processes associated with electron transfer reactions
CT states can be a mixture of locally excited (LE) and radical ion pair (RP; D•+-A•-) states
Controlled by solvent polarity
DMJ-An is an example
Methyl groups inhibit rotation and simplify photophysics
Femtosecond Stimulated Raman Spectroscopy (FSRS) to probe the extent of charge separation in the CT state.
3,5-dimethyl-4-(9-anthracenyl)julolidine
(DMJ)
(An)
FSRS: Basic Principles
Rev. Sci. Instrum., Vol. 75, No. 11, 2004, 4971-4980 Annu. Rev. Phys. Chem., 2007, 58, 461 – 88.
LASER system and Experimental Setup
Annu. Rev. Phys. Chem., 2007, 58, 461 – 88.
FSRS: Advantages
FSRS: Fluorescence Rejection
DMJ-An: Electronic Spectroscopy
ex = 400 nm
An•-
DMJ•+
DMJ-AnCT SimAn
3,5-dimethyl-4-(9-anthracenyl)julolidine
Room Temperature Spectra in THF, λex(TA) = 400 nm
FSRS Spectrum
(λex = 400 nm, λRaman = 800 nm, Room Temperature, THF)
Anthracene localized vibrations (*)
Resonance enhancement
Julolidine localized vibrations (*)
Compare to 9-phenylanthracene (PA)
PA contains localized An Vibrations
DMJ-An CT excited state most closely resembles the PA•- radical anion
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DMJ-An: FSRS Results
FSRS: Basic Principles
Rev. Sci. Instrum., Vol. 75, No. 11, 2004, 4971-4980
Figure 1. Schematic layout of a grating-based compressor with negative dispersion, i.e. the short wavelengths (in blue) come out first.
http://en.wikipedia.org/wiki/Chirped_pulse_amplification#With_gratings
Coherent Anti-stokes Raman Spectroscopy
Increases the intensity of the anti-stokes transitions relative to spontaneous anit-stokes radiation
IR Vibrational Echo Experiments