skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: LOW-TEMPERATURE SPECTROSCOPY OF THE {sup 12}C{sub 2}H{sub 2} (υ{sub 1} + υ{sub 3}) BAND IN A HELIUM BUFFER GAS

Abstract

Buffer gas cooling with a {sup 4}He gas is used to perform laser-absorption spectroscopy of the {sup 12}C{sub 2}H{sub 2} (υ{sub 1} + υ{sub 3}) band at cryogenic temperatures. Doppler thermometry is first carried out to extract translational temperatures from the recorded spectra. Then, rotational temperatures down to 20 K are retrieved by fitting the Boltzmann distribution to the relative intensities of several ro-vibrational lines. The potential of our setup to tune the thermal equilibrium between translational and rotational degrees of freedom is also demonstrated. This can be used to reproduce in a controlled way the regime of non-local thermal equilibrium typically encountered in the interstellar medium. The underlying helium-acetylene collisional physics, relevant for modeling planetary atmospheres, is also addressed. In particular, the diffusion time of {sup 12}C{sub 2}H{sub 2} in the buffer cell is measured against the {sup 4}He flux at two separate translational temperatures; the observed behavior is then compared with that predicted by a Monte Carlo simulation, thus providing an estimate for the respective total elastic cross sections: σ{sub el}(100 K) = (4 ± 1) × 10{sup –20} m{sup 2} and σ{sub el}(25 K) = (7 ± 2) × 10{sup –20} m{sup 2}.

Authors:
; ; ; ; ;  [1];  [2];  [3]
  1. CNR-INO, Istituto Nazionale di Ottica, Via Campi Flegrei 34, I-80078 Pozzuoli (Italy)
  2. CNR-INO, Istituto Nazionale di Ottica, Via N. Carrara 1, I-50019 Sesto Fiorentino (Italy)
  3. INFN, Istituto Nazionale di Fisica Nucleare, Sez. di Firenze, Via G. Sansone 1, I-50019 Sesto Fiorentino (Italy)
Publication Date:
OSTI Identifier:
22521387
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 801; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ABSORPTION SPECTROSCOPY; ACETYLENE; CARBON 12; COMPARATIVE EVALUATIONS; COMPUTERIZED SIMULATION; DEGREES OF FREEDOM; DIFFUSION; HELIUM; HELIUM 4; MOLECULES; MONTE CARLO METHOD; PLANETARY ATMOSPHERES; PLANETS; SATELLITE ATMOSPHERES; THERMAL EQUILIBRIUM

Citation Formats

Santamaria, L., Sarno, V. Di, Ricciardi, I., De Rosa, M., Mosca, S., Maddaloni, P., Santambrogio, G., and De Natale, P.. LOW-TEMPERATURE SPECTROSCOPY OF THE {sup 12}C{sub 2}H{sub 2} (υ{sub 1} + υ{sub 3}) BAND IN A HELIUM BUFFER GAS. United States: N. p., 2015. Web. doi:10.1088/0004-637X/801/1/50.
Santamaria, L., Sarno, V. Di, Ricciardi, I., De Rosa, M., Mosca, S., Maddaloni, P., Santambrogio, G., & De Natale, P.. LOW-TEMPERATURE SPECTROSCOPY OF THE {sup 12}C{sub 2}H{sub 2} (υ{sub 1} + υ{sub 3}) BAND IN A HELIUM BUFFER GAS. United States. doi:10.1088/0004-637X/801/1/50.
Santamaria, L., Sarno, V. Di, Ricciardi, I., De Rosa, M., Mosca, S., Maddaloni, P., Santambrogio, G., and De Natale, P.. Sun . "LOW-TEMPERATURE SPECTROSCOPY OF THE {sup 12}C{sub 2}H{sub 2} (υ{sub 1} + υ{sub 3}) BAND IN A HELIUM BUFFER GAS". United States. doi:10.1088/0004-637X/801/1/50.
@article{osti_22521387,
title = {LOW-TEMPERATURE SPECTROSCOPY OF THE {sup 12}C{sub 2}H{sub 2} (υ{sub 1} + υ{sub 3}) BAND IN A HELIUM BUFFER GAS},
author = {Santamaria, L. and Sarno, V. Di and Ricciardi, I. and De Rosa, M. and Mosca, S. and Maddaloni, P. and Santambrogio, G. and De Natale, P.},
abstractNote = {Buffer gas cooling with a {sup 4}He gas is used to perform laser-absorption spectroscopy of the {sup 12}C{sub 2}H{sub 2} (υ{sub 1} + υ{sub 3}) band at cryogenic temperatures. Doppler thermometry is first carried out to extract translational temperatures from the recorded spectra. Then, rotational temperatures down to 20 K are retrieved by fitting the Boltzmann distribution to the relative intensities of several ro-vibrational lines. The potential of our setup to tune the thermal equilibrium between translational and rotational degrees of freedom is also demonstrated. This can be used to reproduce in a controlled way the regime of non-local thermal equilibrium typically encountered in the interstellar medium. The underlying helium-acetylene collisional physics, relevant for modeling planetary atmospheres, is also addressed. In particular, the diffusion time of {sup 12}C{sub 2}H{sub 2} in the buffer cell is measured against the {sup 4}He flux at two separate translational temperatures; the observed behavior is then compared with that predicted by a Monte Carlo simulation, thus providing an estimate for the respective total elastic cross sections: σ{sub el}(100 K) = (4 ± 1) × 10{sup –20} m{sup 2} and σ{sub el}(25 K) = (7 ± 2) × 10{sup –20} m{sup 2}.},
doi = {10.1088/0004-637X/801/1/50},
journal = {Astrophysical Journal},
number = 1,
volume = 801,
place = {United States},
year = {Sun Mar 01 00:00:00 EST 2015},
month = {Sun Mar 01 00:00:00 EST 2015}
}