Time-resolved photoelectron spectroscopy: the continuing evolution of a mature technique

Abstract

Time-resolved photo-electron spectroscopy (TRPES) has become one of the most widespread techniques for probing nonadiabatic dynamics in the excited electronic states of molecules. Furthermore, the complementary development of ab initio...

Trends in angle-resolved molecular photoelectron spectroscopy

“…To take into account nuclear motion, one of the present challenges, entails repeating calculations, up to some order of magnitude more times, for the description of vibrational states, nonadiabatic couplings, large amplitude motions involved in the dynamics of excited states, like in the current pump–probe processes as described in the companion paper on time dependent processes. 1 This is why an array of approaches, offering reasonable compromise between accuracy and computational cost, is going to be in use also in the near future. The joining of current electronic continuum algorithms and computer codes with those currently developed for the description of the nuclear motion is a pressing issue which is just being developed.…”

“…This methodological corpus builds up a strong potential for future studies of molecular structure and dynamics in real time. 1,444…”

“…This instrumental context will extend significantly the range and the achievements of temporally resolved studies aiming at characterizing in real time molecular structure and intramolecular dynamics triggered by photoabsorption and probed by photoionization, 1 i.e. featuring a so-called “molecular movie”.…”

“…km , the one-photon time delay is expressed by its energy derivative t E; y; j; O ð Þ¼ dZ dE (6) which in the molecular case depends on the emission angles, molecular orientation and photoelectron energy. [10][11][12][13][14] From here, introducing in (1), one arrives at an expression for the differential cross section in MF as a series of angular terms ds FI ðoÞ dk dO ¼ 4p 2 ao X LM A LM Y LM ðy; jÞ (7) where the coefficients A LM depend on the orientation and polarization of the radiation field, as well as on the states I, F and on o. For LP or CP A LM will depend on (b,a) as polar angles, but on full O for general polarization.…”

“…This perspective will be focused on angularly resolved molecular photoionization studies, that is photoelectron angular distributions (PADs), and especially studies with fixed in space molecules molecular frame PADs (MFPADs), in the one photon, multiphoton and strong field regimes, but we only briefly touch the time domain aspects, which are addressed in a companion paper. 1 The lack of spherical symmetry of the molecular potential generates a large number of partial waves in the continuum, whose interference is reflected in the MFPADS, but gets averaged for random orientation. There are several motivations for the continuing intense study of these processes.…”