Vacuum Ultraviolet Pulsed Field Ionization−Photoelectron Study for N₂O⁺ in the Energy Range of 16.3−21.0 eV

Abstract

The vacuum ultraviolet pulsed field ionization-photoelectron (PFI-PE) spectra for N 2 O have been measured in the energy range of 16.3-21.0 eV, covering the vibronic bands of N 2 O + (A 2 Σ + , B 2 Π, and C 2 Σ + ). Many vibronic bands, which were not resolved in previous photoelectron studies, are identified in the present measurement. As observed in the HeI photoelectron spectra of N 2 O, the PFI-PE spectra for N 2 O + (A 2 Σ + and C 2 Σ + ) are dominated by excitation of the ν 1 + (symmetric stretching) and ν 3 + (antisymmetric stretching) modes, along with weak bands due to excitation of both even and odd quanta of the ν 2 + (bending) mode. The simulation of the rotational contours resolved in the PFI-PE bands associated with excitation to N 2 O + (A 2 Σ + , ν 1 + ) 0-1, ν 2 + ) 0, and ν 3 + ) 0-1) has revealed the orbital angular momentum of the outgoing photoelectrons and yielded accurate ionization energies for the formation of these states from N 2 O(X 1 Σ + ).

Spectroscopic study of N2O+(A 2Σ+) by photofragment excitation spectrum

“…To the first-order approximation, the vibrational excitation of an odd quantum of V 2 is forbidden in the linear A 2 ⌺ ϩ ←X 2 ⌸(000) electronic transition. Such type of forbidden vibronic transitions with ⌬V 2 ϭϮ1 were also observed by Dehmer et al 20 and Chen et al 18 in their photoelectron studies and by Aarts and Callomon 4 in their fluorescence emission study, and was interpreted as vibronic interaction between the A 2 ⌺ ϩ and X 2 ⌸ states. 20 This inter- action, however, causes negligibly small shifts of the vibrational energy positions of the A 2 ⌺ ϩ state compared to the Fermi-resonance interactions, as seen from Ref.…”

“…21 The vibrational frequencies 1 ͑symmetry stretching͒, 2 ͑bending͒, and 3 ͑anti-symmetric stretching͒ of N 2 O ϩ (A 2 ⌺ ϩ ) are known to be around 1346, 611, and 2450 cm Ϫ1 , respectively, as determined from the fluorescence emission study, 3 FIBLAS studies, [11][12][13][14][15][16] and photoelectron measurements. 18 Based upon the known vibrational frequencies of N 2 O ϩ (A 2 ⌺ ϩ ) and several observed A 2 ⌺ ϩ →X 2 ⌸(000) vibronic transitions in emission studies, tentative assignments were performed to the PHOFEX spectrum. It was found that except for a few peaks in the low excitation energy region in Fig.…”

“…[3][4][5][6][7][8][9][10] Larzilliere et al [11][12][13][14][15][16] have investigated several lowest levels of the A 2 ⌺ ϩ state in detail with highly resolved rovibrational FIBLAS spectroscopy. Very recently, Ng and co-workers 18 performed a vacuum ultraviolet pulsed field ionization-photoelectron ͑PFI-PE͒ study, and have observed some new vibrational levels of the A 2 ⌺ ϩ state.…”

“…Despite of extensive works regarding the X 2 ⌸ state and several lowest vibrational levels of the A 2 ⌺ ϩ state, there has been very few reports about the high vibrational levels of the A 2 ⌺ ϩ state, especially levels higher than the ͑300͒ level. Since the vibrational frequencies of the A 2 ⌺ ϩ state have the relations 3 ϳ2 1 ϳ4 2 as determined by several independent works, 3,18,19 Fermi-resonance couplings are expected to occur among vibrational levels (…”

Penning ionization of N2O molecules by He*(2S3,1) and Ne*(P2,3) metastable atoms: Theoretical considerations about the intermolecular interactions

“…22 Isodensity contour maps of the squared molecular orbitals ͓lowest unoccupied molecular orbital ͑LUMO͒, highest occupied molecular orbital ͑HOMO͒, "nitrogen and oxygen lone pairs"͔, obtained with the ab initio calculations illustrated in the previous paper, 13 are reported in Figs. Specifically, in the present investigation it has been taken into account that N 2 O molecule can be ionized in several electronic states ͑X 1 2 ⌸, à 1 2 ⌺ + , and B 2 2 ⌸, for He * ; X 1 2 ⌸ and à 1 2 ⌺ + for Ne * ͒ each one characterized by electron removal from a specific molecular orbital.…”