Pump-probe spectroscopy of H-bonds: Saturation kinetics and spectral transformation during and after pumping

Abstract

Excited state kinetics of neutral transition metal atoms by stimulated emission pumping: V * (3d 4 4s,a 4 D)+ hydrocarbonsThe saturation kinetics of the H-bond absorption spectra in a strong laser field is described as a level-crossing problem with diffusional motion along the reaction coordinate. The full analogy with kinetics and rate of electron transfer reactions is emphasized when vibrational relaxation to the ground state is negligible. In this case, the transition rate saturates with a field strength reaching the diffusional regime limited by the friction in the ground or excited state. Taking vibrational relaxation into consideration changes qualitatively the kinetics of approaching the stationary level populations and absorption of pumping light. The fast relaxation results in significant desaturation of the light induced transitions and a shortening of the transient time. The absorption spectra of the weak probe light in the context of two-level and three-level models show either loss or gain in the red wing, as well as bleaching and superabsorption in the corresponding transmission spectra. The time evolution of these spectra, after switching the strong field on and off, was studied.

Variation of the Resonant Transfer Rate When Passing from Nonadiabatic to Adiabatic Electron Transfer

“…The last phenomenon was discovered independently in two simultaneously published papers, refs and . The latter is addressed rather to the inner sphere low frequency vibrations such as in H-bonded complexes in water, studied later by pump−probe spectroscopy. − The former addressed more specifically the outer sphere electron transfer in Debye polar solvents where Here τ L = τ D ε 0 /ε is the longitudinal relaxation time of dielectric polarization related to the Debye relaxation time τ D , through the ratio of the optical (ε 0 ) and static (ε) dielectric constants. Later on, the phenomenon of diffusional control in the reaction space, which became known as the dynamical solvent effect, was reproduced in a number of publications and observed experimentally .…”

Solvent-Controlled Theory Analysis of Chirped Pulse Excitation of Molecules in Solutions

“…It allows us to simplify the problem by considering only the equations for density matrix elements diagonal with respect to electronic indices. ,, It is worthy to note that in spite of the fast electronic dephasing approximation, such an approach does take into account vibrational coherences within both the ground and excited electronic states. A similar approach to the spectroscopy of H-bonds in a strong infrared field has been proposed by Burshtein et al − …”

“…22,23,29 It is worthy to note that in spite of the fast electronic dephasing approximation, such an approach does take into account vibrational coherences within both the ground and excited electronic states. A similar approach to the spectroscopy of H-bonds in a strong infrared field has been proposed by Burshtein et al [30][31][32] In essence, approach 22,23,29 for strong pulse interaction with large molecules in solutions is closely related to the theory of electron-transfer reactions under strong interaction (solventcontrolled limit). [33][34][35][36] Really, one can consider an electronic optical transition as an electron-transfer reaction between "photonic replication" 1′ of the ground electronic state 1 and the excited electronic state 2 (or between state 1 and "photonic replication" 2′ of state 2) induced by interaction with electromagnetic radiation of frequency ω 22,23 (see Figure 1) For chirped pulse excitation the field amplitude can be represented in the form:…”