New bands of deuterated nitrous acid (DONO) in the near-infrared using FT-IBBCEAS

Ranjini Raghunandan,Johannes Orphal,Albert A Ruth

doi:10.1016/j.cpletx.2020.100050

Abstract

The first measurements of near-infrared bands of deuterated nitrous acid (DONO) are presented. The measurements were made using Fourier-Transform Incoherent Broad-Band Cavity-Enhanced Absorption Spectroscopy (FT-IBBCEAS) in the 5800–7800 cm−1 region. Two bands of trans-DONO centred at 6212.029 and 7692.496 cm−1 were observed and assigned to the 2ν1+ν3 combination and 3ν1 overtone vibrations, respectively. Their rotational band structure was satisfactorily reproduced using PGOPHER. For cis-DONO the 3ν1 band was observed at ~7302.5 cm−1. In addition, new bands centred at 6142.5 cm−1 and 7607.6 cm−1 were quite confidently assigned to the 2ν1+ν3 and 3ν1 vibrations of deuterated nitric acid, DNO3, respectively.

Highlights

Nitrous acid, HONO, has been the subject of numerous spectroscopic studies [1,2,3,4,5,6,7,8,9,10,11,12]
New bands centred at 6142.5 cm−1 and 7607.6 cm−1 were quite confidently assigned to the 2ν1+ν3 and 3ν1 vibrations of deuterated nitric acid, DNO3, respectively
We report measurements of the 2ν1+ν3 and the 3ν1 bands of trans-DONO and the 3ν1 band of cis-DONO in the near-infrared region using Fourier-Transform Incoherent Broad-Band CavityEnhanced Absorption Spectroscopy (FT-IBBCEAS) [27,28,29]

Summary

Introduction

HONO, has been the subject of numerous spectroscopic studies [1,2,3,4,5,6,7,8,9,10,11,12]. The near-infrared region is interesting in these aspects because it might play a role in photodissociation from vibrationally excited (“solar pumped”) states [20], and because it is well suited for fast HONO detection in chemical reactions [21]. The trans-isomer is the thermodynamically preferred configuration in both cases, as determined by measurements in the microwave region [24]. The zero-point corrected ground state energies of the cis-isomers of HONO and DONO lie ~107 cm−1 and ~114 cm−1 above that of the corresponding trans-form [23]. The ground states of the cis-isomers of both isotopologues are thermally populated at room temperature (296 K) at somewhat less than 60% of that of the trans-form. No absorption band of DONO has been measured upto-date in the near-infrared region.

Present address

Experimental

Results and discussion

Cis-DONO

Trans-DONO

Conclusions