Femtosecond stimulated emission pumping:

Abstract

Femtosecond stimulated emission pumping in conjunction with femtosecond photoelectron spectroscopy is used to cm , 7 cm higher than that of bare I . As the I loses energy to the CO molecules, the wavepacket frequency increases 2 2 2 21linearly at a rate of 3.8 cm / ps during the initial 3 ps of coherence. The rate of energy transfer can be determined either by this increase in vibrational frequency or by the shift of the measured photoelectron spectrum. No solvent evaporation during the first 7 ps is observed, but three CO molecules evaporate on a microsecond time scale.

Femtosecond Time-Resolved Photoelectron Spectroscopy

“…A series of papers by Davis et al [209][210][211] explored dynamics in I 2 -(X) n clusters (X ) Ar and CO 2 ) subsequent to coherent vibrational excitation of the I 2 -chromophore at a series of excitation energies E exc . The relaxation dynamics of the I 2 -were followed using two observables in the TRPE spectra.…”

The interaction of negative charge with carbon dioxide – insight into solvation, speciation and reductive activation from cluster studies

“…In addition, dephasing of vibrational wavepackets is observed on the ps timescale for the I-I vibration of the solvated ion. However, this dephasing is not associated with fragmentation of the clusters, since no solvent molecules are evaporated during the first few ps after wavepacket excitation [155].…”

“…170-180 meV for the first eight CO 2 solvent molecules [130,153]. Their interaction with the ion increases the vibrational frequency of the I À 2 ion in its electronic ground state by several cm À1 in I À 2 Á ðCO 2 Þ n [154,155]. The blue shift was rationalised by attractive interactions with CO 2 molecules around the I-I bond and charge delocalisation to the solvent, similar to that observed in halide-CO 2 clusters (see Section 4.1).…”

Vibrational polarization beats in femtosecond coherent anti-Stokes Raman spectroscopy: A signature of dissociative pump–dump–pump wave packet dynamics

“…[1][2][3][4][5][6] This ability to selectively pump large amounts of energy into a specific molecular motion represents an important first step towards control of chemical reaction dynamics. Vibrational excitation was produced by a sequence of two femtosecond pulses; a ''pump'' pulse creating a wave packet on an excited electronic state, followed by a ''dump'' pulse of longer wavelength that drops the wave packet back to the ground electronic state at higher vibrational energy than the initial state.…”

“…1,2 Neumark and co-workers have used pump-dump to create and detect ground state wave packets as high as 98% of the dissociation threshold in gas phase I 2 Ϫ using femtosecond photoelectron spectroscopy. 3,4 Finally, Knopp, Pinkas, and Prior have generated and detected ground state wave packets in I 2 having up to half of the ground state dissociation energy, using two-dimensional time delay coherent anti-Stokes Raman spectroscopy ͓͑TD͒ 2 CARS͔. 5,6 Whereas the above mentioned schemes use femtosecond pulses and generate the desired wave packet within a single vibrational period, there are also well-established techniques for the generation of highly excited vibrational states on time scales much longer than a vibrational period.…”