The infrared spectroscopy and photochemistry of NO3 trapped in solid neon

Abstract

NO(3) can be stabilized in solid neon either by codeposition at 4.3 K of a Ne:O(2) mixture with a Ne:NO mixture that has been passed through a microwave discharge or, in higher yield, by codeposition of a Ne:NO mixture with a Ne:O(2) mixture, followed by annealing of the deposit at approximately 7 K and exposure of the solid to near ultraviolet radiation. All of the previously reported bands of NO(3) between 700 and 3000 cm(-1) were observed, most with neon-matrix shifts of less than 2.5 cm(-1). The infrared spectra of eight isotopic species of NO(3) were obtained. The observed isotopic shifts demonstrate the occurrence of extensive mixing of ground-state levels of e(') symmetry and their strong vibronic interaction with the B (2)E(') state. Photodissociation of NO(3) by irradiation of the deposit at wavelengths longer than 520 nm leads to new absorptions near the fundamentals of NO and O(2) and other new absorptions at relatively low frequencies. These absorptions were depleted and NO(3) regenerated by subsequent near ultraviolet irradiation of the deposit, suggesting the stabilization of a weakly bound NO(O(2)) complex in solid neon.

Conflicting Observations Resolved by a Far IR and UV/Vis Study of the NO3 Radical

“…Important recent studies include: 1) photoelectron (PE) spectroscopic studies of both the nitrate anion [6,7] and the NO 3 radical, [8] 2) laser-induced fluorescence (LIF) spectra of the nitrate radical, [9,10] as well as a recent reanalysis of the vibronic levels obtained from these spectra, aided by non-adiabatic computations, [11] 3) the analysis of high-resolution diode laser and FTIR gas phase spectra which were obtained in the region 700 to 1520 cm À1 , [12,13] and later extended to 1300-2800 cm À1 [14][15][16] and to the near infrared, [17] and 4) a neonmatrix FTIR study on NO 3 in the range from 450 to 6000 cm À1 . [18] From the analysis of the recent spectra, D 3h symmetry was determined for the free NO 3 radical in the X $ 2 A 2 ' ground state. [11,16,18] However, no consistent assignment of the in-plane ground state vibrational levels exists.…”

Communication: MULTIMODE calculations of low-lying vibrational states of NO3 using an adiabatic potential energy surface

“…It has been the focus of a large body of spectroscopic work due to its complexity and difficulty in making state assignments. [1][2][3][4][5][6][7][8][9][10][11][12][13][14] Theoretically, numerous papers have appeared dealing with various aspects of the electronic structure and vibrational analysis [15][16][17][18][19][20][21] and we refer the reader to those papers for details. We note that theoretical work on vibrational assignments done by Stanton has used a model vibronic Hamiltonian, developed by Köppel−Domcke−Cederbaum, 22 with high-level ab initio input and some empirical scaling of the diabatic coupling to obtain good agreement with experiment.…”

Intermediates Involved in the Oxidation of Nitrogen Monoxide: Photochemistry of the cis‐N2O2⋅O2 complex and of sym‐N2O4 in Solid Ne Matrices

“…These bands revealed no resolved 16/18 O isotopic splitting, which indicated only a weak coupling between the two weakly From the spectra shown in Figure 5, and from the observation that solely the mixed isotopologue NA C H T U N G T R E N N U N G ( O-substituted carrier of the broad band at about 1606 cm À1 was not formed in this experiment. These additional bands also appeared upon exposure of Ne/O 2 /NO matrices to UV irradiation (l = 260-400 nm), [53] in which the broad band observed at 1606 cm À1 on IR photolysis was replaced by a much sharper band at 1607.5 cm À1 . This band is assigned to the (NO 2 ) 2 dimer complex already detected in the N 2 O 4 photolysis experiment.…”

“…[1,53] As shown in Figure 4, the ON·O 2 complex produced under these conditions displays a prominent and slightly split N=O stretching band at 1871.9 cm À1 that strongly increases with the relative amount of O 2 in the deposit. This band also corresponds to both a weak O=O stretching-band doublet located at 1540.0 and 1531.1 cm…”