Infrared laser spectroscopy of the ν3 fundamental of HCO+

Abstract

Eighteen lines in the P and R branches of the ν3 band of HCO+ have been measured by diode-laser absorption spectroscopy using a velocity modulation technique. The position of the band center is 2183.9505(51) cm−1.

ALMA INVESTIGATION OF VIBRATIONALLY EXCITED HCN/HCO+/HNC EMISSION LINES IN THE AGN-HOSTING ULTRALUMINOUS INFRARED GALAXY IRAS 20551−4250

“…Since the energy level of v 2 = 1 is the lowest, its vibrational excitation is the simplest (Townes & Schawlow 1975;Amano 1983;Davies et al 1984;Kawaguchi et al 1985). The HCN v 2 = 1f J = 4-3, J = 3-2, and HNC v 2 = 1f J = 3-2 emission lines have previously been detected in the LIRG NGC 4418 (L IR ∼10…”

“…However, the other dense gas tracers, HCO + and HNC, also have absorption features at infrared ∼12 μm and ∼21.5 μm, respectively (Davies et al 1984;Kawaguchi et al 1985;Burkholder et al 1987), and could therefore be vibrationally excited to v 2 = 1 by infrared radiative pumping. If the infrared radiative pumping mechanism is responsible for the enhanced HCN J-transition emission at v = 0 in AGNs, its efficiency must be particularly high for HCN only.…”

ALMA HCN AND HCO+ J = 3 − 2 OBSERVATIONS OF OPTICAL SEYFERT AND LUMINOUS INFRARED GALAXIES: CONFIRMATION OF ELEVATED HCN-TO-HCO+ FLUX RATIOS IN AGNS

“…Like HCN, infrared radiative pumping should also work for HCO + , because HCO + can be excited to the v 2 =1 level by absorbing infrared 12 µm photons (Davies et al 1984;Kawaguchi et al 1985). The infrared radiative pumping rate (P IR ) is…”

“…The proposed decrease in HCO + abundance could also occur in turbulent molecular gas in a starburst with strong cosmic rays (Papadopoulos et al 2007). In addition, HCO + , as well as HCN, can be vibrationally excited by absorbing infrared 12 µm photons (Davies et al 1984;Kawaguchi et al 1985), and the HCO + J-transition flux at v=0 could also be increased through the action of infrared radiative pumping. Given these remaining theoretical ambiguities, further detailed interferometric observations of galactic nuclei where the energetic roles of AGNs are reasonably well estimated are an important step toward better clarifying whether elevated HCN-to-HCO + flux ratios can indeed operate as good indicators of AGNs.…”

Multiresonant Spectroscopy and the High-Resolution Threshold Photoionization of Combustion Free Radicals

“…[15][16][17][18] It is the first polyatomic cation to be characterized by application of infrared and microwave absorption spectroscopies. [19][20][21][22][23][24][25][26][27][28] This system continues to serve as a prominent point of contact between experiment and ab initio theories of molecular electronic structure. [29][30][31][32][33] However, despite this fundamental importance and the great deal of experimental work that had been carried out on HCO + over the last 25 years, laboratory measurements had securely determined spectroscopic parameters only for the ground state and three fundamental vibrationally excited states of this system.…”