Transient absorption of PE/ch induced by 50 fs pump pulses at 400 nm. (a) Transient spectrum at . The stationary bands for absorption and SE are also shown. Arrows indicate the motion of the wave packet back and forth along the probe wavelength. (b) Kinetic traces for selected probe wavelengths.
Fourier analysis of perylene vibrational coherence induced by 50 pump pulses (as in Fig. 1). Wavelength-dependent Fourier power spectra of the oscillatory signal of PE/ch pumped at (a) 444 nm and (b) 400 nm. (c) Fourier power spectra averaged over 350–600 nm for the excitation at 444 nm (black line) and for 400 nm pump (filled area).
Spectral dependence of the amplitude of the dominant perylene mode at (as in Fig. 1).
Spectral composition of transient absorption spectra for a molecular system . The electronic three-level system with transition origins at and is homogeneously broadened by . The system is excited by a 50 fs pump and observed by a -probe pulse. (a) Nonoscillatory part of the transient absorption signal including BL, SE, and ESA . The stationary absorption and SE bands are also shown. [(b) and (c)] Spectral characteristics of the impulsive SR process. (b) PA components forming the PA amplitude of the SR process. (c) The absorptive cos amplitude (black line) and dispersive sin amplitude (thin black line) resulting in the PA amplitude (gray filled area).
Phase characteristics of the SR process for the molecular system of Fig. 4. (a) Contributions from processes. The normalized PA amplitudes and are given for comparison. (b) The phase of the coherent motion together with the component. (c) Difference between phases of oscillation in the ground and excited states for different pump pulse widths.
Spectral composition of transient absorption spectra for a system containing a low and a high frequency mode with vibrational quantum numbers in each electronic state. The modes are displaced upon excitation by and . The system is excited by a 50 fs pulse at and monitored by a -probe pulse. For notation see the legend to Figs. 4 and 5.
Effect of detuning on the impulsive SR process for the molecular system of Fig. 6. The excitation is located at the absorption origin (, gray line), above (, thin black line), and below (, thick black line). (a) PA amplitude and (b) contribution from the ground and (c) excited state .
Transient absorption spectra and SR contributions for with vibrational quantum numbers and displacements , , and . The homogeneously broadened system is excited by a 50 fs pump pulse at and monitored by a -probe pulse. (a) Nonoscillatory component and the absorption and emission bands. [(b) and (c)] Spectral characteristics of the SR process. (b) PA amplitude of the SR response for the two low frequencies and for mode beating . (c) Spectral dependence of the phases of oscillations.
Influence of probe pulse properties on the transient absorption signal and its composition. The low and high frequency modes are displaced by and and span quantum numbers and , respectively. The system is excited by a 50 fs pump pulse and monitored by a probe pulse which has a linear chirp (LC, thin black line), is an ultrashort transform-limited Gaussian (, thick line), or is a pulse (, gray line). (a) contribution and the absorption and emission bands. [(b) and (c)] Spectral characteristics of the SR process.
The effect of LC in the pump pulse. The molecular system of Fig. 9 is excited by a pulse at and probed by a -probe pulse. The gray filled area and thick black lines correspond to positive chirp and negative chirp , respectively. Thin black lines refer to , i.e., to a transform-limited pump pulse. (a) PA amplitude of oscillations and [(b)–(d)] contributions .
Molecular model for electronic states and a single active vibrational mode, of frequency , along dimensionless normal coordinate . Vibrational activity is controlled by a structural displacement upon electronic excitation from the ground state. and are the origin frequencies for absorption and ESA, respectively.
Energy ladder diagrams for molecular model with two optically active modes. A mode is represented here by vibrational states in each electronic state. Vibronic pathways involve the creation of vibrational coherence by the first two pump interactions [blocks , , ), off which the field is scattered (blocks ,…) to give signal. The process is divided into types , , and . In general each diagram represents a family of diagrams which differ in the way the vibrational states , , are involved. Solid and dotted arrows correspond to ket and bra propagations of the density matrix element, respectively, and wavy lines indicate electronic polarization at the appropriate frequency. It is assumed that only is populated initially. Response functions corresponding to the complete diagram (Refs. 53–55) are indicated.
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