Vibronic coupling in excited states of acetone

Abstract

Photoelectron spectroscopy of Rydberg states of acetone-h 6 and -d 6 populated by two-or three-photon excitation has been employed to unravel the vibronic description of excited-state levels. For the 3p Rydberg states vibronic transitions have been reanalyzed, leading to various reassignments and the observation of hitherto nonreported transitions. In addition, several ionic vibrational frequencies could be determined. At higher excitation energies previously identified, and in the present study newly identified, members of two Rydberg series have been characterized. The ns Rydberg series was explored up to the 8s state, the nd series up to the 7d state. Based upon the unambiguous assignments of vibronic character that we obtain for excited-state levels, various valence-Rydberg and Rydberg-Rydberg vibronic coupling pathways come to light and are analyzed.

Spectroscopy and dynamics of excited states in maleimide and N-methyl maleimide: Ionic projection and ab initio calculations

“…We have demonstrated that the complementary approach of concentrating on the energy resolution in the frequency domain-as opposed to time resolution in the time domain-enables one to disentangle vibronically coupled states as well. 1,2,6 As might be expected, these studies show that the frequency domain approach has its own distinct advantages, in particular for close-lying states that ionize to the same electronic ionic state. Application to complementary ionization channels has, however, not been done so far, but is one of the subjects of interest in the present study on maleimide and N-methyl maleimide.…”

“…The same table shows that the band shifted by 280 cm Ϫ1 to the red cannot be assigned to an a 1 vibration. Although this frequency is similar to that of 12 in the ground state, it is hard to imagine that it would be the 12 1 0 hot band, because that would imply loss of symmetry in the excited state, and lead us to expect that the 12 0 1 transition Oscillator strength…”

“…2, it is seen that the relevant orbitals of b 1 symmetry can roughly be char- acterized as being localized on the nitrogen atom (2b 1 ϭ CvC ) and the CvC bond (3b 1 ϭ N ). The in-plane 12a 1 and 9b 2 orbitals consist of the symmetric and antisymmetric combination of the oxygen lone pair orbitals, respectively, and will be designated as n o ϩ and n o Ϫ . In the following, we will see that the lower-lying excited states of interest in the present studies are in first approximation described as excitations of electrons from these -and n orbitals to the 2a 2 ( *) orbital.…”

Excited and ionic states of formamide: An excited-state photoelectron spectroscopy and ab initio study

“…In several studies we have by now shown the kind of detail that can be reached. For example, in similar studies on the excited-state manifold of acetone, 32 we demonstrated that considerable reassignments needed to be done of spectra that for a long time were considered as ''solved.'' One other aspect that emerged from that particular study was how well wave functions could be resolved in terms of vibronically interacting states using the technique of excited-state photoelectron spectroscopy.…”

A multiphoton ionization study of acetone using time-of-flight mass spectrometry

“…The lowest energy transition from the ground state to the 1 A 2 (n y →π * ) [1,2], the transition to the 3s ( 1 B 2 ) Rydberg state [3][4][5][6], and those to the three 3p Rydberg states have been observed [7][8][9][10][11][12][13][14][15]. The 3p x ( 1 A 2 ), 3p y ( 1 A 1 ), and 3p z ( 1 B 2 ) Rydberg states of acetone are positioned at 7.36, 7.41, and 7.45 eV, respectively [9,10,12,14,15]. The 3p Rydberg spectrum of acetone differs from that of the 3s Rydberg state, as the absorption in the 3p region is very weak and the zero point isotopic shift between the assigned origin bands of acetone and acetone-d 6 is small.…”