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