A Discussion on photoelectron spectroscopy - Photoelectron spectra of some polyatomic molecules

Abstract

The photoelectron spectra of ethylene, ethylene-d4, ammonia, and ammonia-d3 have been measured using a hemispherical high resolution electrostatic spectrometer and the 584 MATHS SYMBOL helium resonance line as the exciting radiation. Many ionization potentials have been determined for each compound and vibration structure associated with the transitions leading to the various ionization potentials has in many cases been well resolved. It has been possible to suggest reasonable assignments for the corresponding vibrational modes. The photoelectron spectra of MATHS FORMULA obtained using neon radiation (736 and 744 MATHS SYMBOL) shows a progression of twenty-one vibrational transitions, with maxima at v = 1 and v = 7. This is larger than the number of vibrational transitions observed with the 584 MATHS SYMBOL helium line and it is postulated that the extra structure observed arises from ionization processes from a long-lived excited state of oxygen.

Revisiting the photoabsorption spectrum of NH3 in the 5.4–10.8 eV energy region

“…Furlan et al 53 explored singlet excited states in the 5.50-11.0 eV energy range also discussing the classification of the Rydberg series, while Burton et al 50,51 reported absolute dipole oscillator strengths for theà ←X transition. The He(I) photoelectron spectrum of Edvardsson et al 15 relevant to this work obtained an adiabatic ionization energy for theX 2 A ′′ 2 state of 10.186 eV in good agreement with the Branton et al 44,45 value of 10.14 eV as well as from the zero kinetic energy photoelectron spectrum of Reiser et al, 48 whereas the photoionization data of Locht and co-workers 43 report a value of 10.072 eV.…”

“…The lowest ionization energy has been determined by different experimental techniques, although we still note a lack of agreement between the different vertical and adiabatic values. 15,39,[43][44][45][46][47][48] Nevertheless, the experimental adiabatic value which is needed to calculate the quantum defects associated with transitions to Rydberg orbitals results from the removal of an electron from the lone pair n H and is here taken from Ref. 48 to be 10.186 eV (1a ′′…”

“…4 Amongst many other areas, it is also of interest in the chemistry and kinetics of the surface nitridation process in the semiconductor plasma industry 5 and synthesis of ammonia directly from air and water under ambient conditions. 6 NH 3 and its isotopologues have been comprehensively explored by experimental and theoretical methods, the former investigating photoabsorption 2,3, and photodissociation, 8,10,15,[33][34][35][36][37][38] photon and multiphoton ionization, 17,23,27,[39][40][41][42] photoelectron spectroscopy, 15,39,[43][44][45][46][47][48] and electron energy loss and electron impact spectroscopies; 47,[49][50][51][52][53][54][55] the latter on the electronic-state spectroscopy of valence, Rydberg and lowest ionic states, [56][57][58][59][60][61][62][63][64]…”

Time‐Resolved Photoelectron Spectroscopy of Nonadiabatic Dynamics in Polyatomic Molecules

“…whered αα+ Γµhl (q) is the value of d αα+ Γµhl (q; R) averaged over R. Within this approximation, the overlap integral between the molecular vibrational state and the cation vibrational state determines the ionization efficiency to each cation vibrational state [13,42,[79][80][81][82][83][84][85]. The Franck-Condon factors are determined by the relative equilibrium geometries of the electronic states of the neutral (Φ α (r; R)) and cation (Φ α+ (r ; , R)) [13,42].…”