Energy Transfer into Molecular Vibrations and Rotations by Recoil in Inner-Shell Photoemission

Abstract

A mixture of CF_{4} and CO gases is used to study photoelectron recoil effects extending into the tender x-ray region. In CF_{4}, the vibrational envelope of the C 1s photoelectron spectrum becomes fully dominated by the recoil-induced excitations, revealing vibrational modes hidden from Franck-Condon excitations. In CO, using CF_{4} as an accurate energy calibrant, we determine the partitioning of the recoil-induced internal excitation energy between rotational and vibrational excitation. The observed rotational recoil energy is 2.88(28) times larger than the observed vibrational recoil energy, well in excess of the ratio of 2 predicted by the basic recoil model. The experiment is, however, in good agreement with the value of 2.68 if energy transfer via Coriolis coupling is included.

Hard x-ray photoelectron spectroscopy on heavy atoms and heavy-element containing molecules using synchrotron radiation up to 35 keV at SPring-8 undulator beamlines

“…the resolving power E/ΔE higher than 5000 (where E is the kinetic energy of electron and ΔE the instrumental resolution), are quite scarce. Up to now, the GALAXIES beamline at the SOLEIL synchrotron [2,3] has been the only facility for high-resolution HAXPES experiments on atomic and molecular science and has been achieving significant results on double-core-hole spectroscopy [4][5][6][7], recoil effects [8][9][10], ultrafast phenomena [11][12][13], post-collision interaction (PCI) [14,15], resonant Auger processes [16][17][18][19][20], and very recent studies on aqueous solution [21,22]. The experiments at the GALAXIES beamline, however, are limited to the excitation energy ranging between 2.3 and 12 keV, while experiments with much higher photon energy are quite scarce.…”

Hard x-ray spectroscopy and dynamics of isolated atoms and molecules: a review

“…In this framework, to identify subtle rotational recoil effects in a linear diatomic molecule, again CO, experiments were conducted on a mixture of CO with another system, namely CF 4 , which, being centrosymmetric, does not show rotational effects following the core ionization of the carbon central atom [64]. In Figure 29 we show C 1s photoelectron spectra of CF 4 taken as a function of photon energy.…”

Recoil-induced dissociation in hard-x-ray photoionization

“…This generally justifies the use of the time-honored Franck-Condon (FC) principle in the soft-x-ray region where the momentum exchange between the photoelectron and molecules manifests itself as small rotational and translational Doppler broadenings as well as a small recoil shift of the vibrational resonances due to momentum transfer to the center-of-gravity (CG) of the molecule. In the last decade, the interest in this field has increased, mainly due to the available super-high spectral resolution in the photoelectron energy range below 10 keV which allowed observation of recoil-induced vibrational excitation [4][5][6][7][8], translational and rotational recoil shifts [9], the rotational Doppler effect [10][11][12][13][14], and recoil-induced Doppler splitting [10,15,16]. The recoil shifts of the photoelectron lines were observed also in solids such as graphite [17], heavy fermion material LiV 2 O 4 [18], and Al and Au metals [19].…”