Photofragment spectroscopy of N+2 in the near UV

Abstract

Photofragment spectroscopy of N~-has been studied in the wavelength range 343~404 nm using an excimer-pumped dye laser with a spectral resolution of 0.2 cm-1. The observed bands are assigned to transitions from the v" =23-26 levels of the X2S~ state to highlying rovibrational levels (v'~ 46-48) of the B 2S,+ state, forming quasibound (predissociating) states above the dissociation limit N+(3P)+ N(4S°). Measurement of the photofragment kinetic energies allows to establish an absolute energy scale for the transitions with respect to the dissociation limit. Molecular constants for the lower and upper states of the observed transitions are determined. The measurements allow the first direct determination of the N2 + dissociation energy Do°(N~-). Some high-resolution (0.04 cm -1) measurements show the fine-structure splitting and lifetime broadening of the excitation lines.

Direct measurement of the N+2 dissociation energy

“…The upper level N'= 15 of this transition lies W = 3 cm-1 above the lowest dissociation limit [1]. Using the relation D°,,=(hv-W)+ B~,,N"(N" + I) we obtain the dissociation energy D°,, = 34793.4 ± 1 cm-1 of the rotationless v" = 19 level.…”

“…The description of the photofragment machine is given in the previous paper [1]. The ion beam apparatus is essentially the same as used in the earlier measurement, with the completion of a new multichannel detector to collect simultaneously N + fragments of various energies.…”

Observation of Continuum State Dissociation Enables the Determination of N2 Bond Dissociation Energy to Spectroscopic Accuracy

“…Based on the well-known ionization energies of N and N 2 , the BDE of N 2 was calculated to be 78691 ± 6 cm −1 , which is compared with the currently adopted value of 78674 ± 4 cm −1 in the ATcT. 14,21 Surprisingly, this measurement was not included in the TN for determining the BDE of N 2 adopted in the ATcT. 16 Recently, we have reported a new experiment for measuring the accurate BDEs of 14 N 2 , 14 N 15 N, and 15 N 2 on the newly constructed VUV-pump-VUV-probe time-sliced velocity-mapped imaging (VUV-VUV-TS-VMI) setup.…”

“…In 1991, Hertzler et al performed a detailed investigation on the spectrum of N 2 + ion, from which the accurate BDE of N 2 + was determined to be 70248 ± 6 cm –1 . Based on the well-known ionization energies of N and N 2 , the BDE of N 2 was calculated to be 78691 ± 6 cm –1 , which is compared with the currently adopted value of 78674 ± 4 cm –1 in the ATcT. , Surprisingly, this measurement was not included in the TN for determining the BDE of N 2 adopted in the ATcT …”