A near infrared line list for \NH: Analysis of a Kitt Peak spectrum after 35 years

TL;DR

This study analyzes a 35-year-old Fourier Transform spectrum of ammonia in the near-infrared, providing the first detailed line list and experimental energies for ammonia in the 7400-8600 cm-1 region, extending known vibrational states.

Contribution

It presents the first comprehensive assignment and experimental energy data for ammonia in this spectral region, using a combination of variational line lists and the MARVEL procedure.

Findings

Identified 8468 ammonia lines and assigned 2474 to 21 bands.

Provided 1692 experimental energies in the 7000-9000 cm-1 range.

Extended the known vibrational-excited states of ammonia.

Abstract

A Fourier Transform (FT) absorption spectrum of room temperature NH3 in the region 7400 - 8600 cm-1 is analysed using a variational line list and ground state energies determined using the MARVEL procedure. The spectrum was measured by Dr Catherine de Bergh in 1980 and is available from the Kitt Peak data center. The centers and intensities of 8468 ammonia lines were retrieved using a multiline fitting procedure. 2474 lines are assigned to 21 bands providing 1692 experimental energies in the range 7000 - 9000 cm-1. The spectrum was assigned by the joint use of the BYTe variational line list and combination differences. The assignments and experimental energies presented in this work are the first for ammonia in the region 7400 - 8600 cm-1, considerably extending the range of known vibrational-excited states