Experimental and Theoretical Study of the Broadening and Shifting of N2H+ Rotational Lines by Helium

Year: 2010

Authors: Buffa G., Tarrini O., Dore L., Meuwly M.

Autors Affiliation: CNR – IPCF Largo Pontecorvo 3 I-56127 Pisa (Italy);
Dipartimento di Chimica “G. Ciamician” Universita’ di Bologna, Via Selmi 2, I-40126 Bologna (Italy);
Department of Chemistry Brown University, Providence RI 02912 (USA);
Department of Chemistry, Klingelbergstr. 80, 4056 Basel, Switzerland

Abstract: Pressure broadening and pressure shift of N2H+ rotational lines perturbed by collisions with He are studied for the first time using experiment and theory. Results are reported from measurements at 88 K for the rotational transitions j = 3 <- 2, 4 <- 3, 5 <- 4 and 6 <- 5 with frequencies raging from 0.28 to 0.56 THz. The agreement between experiment and theoretical data derived from close coupling calculations confirms the reliability of a theoretical framework used for state-to-state transition rates of interest in the interpretation of spectroscopic data from interstellar molecular clouds. The influence of hyperfine effects on shifts and widths of the rotational lines is discussed in detail. Although in principle possible, experiment and theoretical considerations lead to the conclusion that hyperfine effects only play a minor role. Journal/Review: CHEMPHYSCHEM

Volume: 11 (14)      Pages from: 3141  to: 3145

More Information: LD acknowledges financial support from MIUR (PRIN 2007 funds, project \’Trasferimenti di energia, carica e molecole in sistemi complessi\”) and from the University of Bologna (RFO funds). MM acknowledges financial support from the Schweizerischer Nationalfonds (grant 200021-117810).
KeyWords: ab initio calculations; cluster compounds; helium; hyperfine effects; rotational spectroscopy
DOI: 10.1002/cphc.201000230

Citations: 11
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