Synthesizing primary molecular relaxation processes in excitable gases using a two-frequency reconstructive algorithm

Andi G. Petculescu*, Richard M. Lueptow

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

36 Scopus citations

Abstract

Identifying molecular relaxation processes in excitable gases remains challenging. An algorithm that reconstructs the primary relaxation processes is presented. Based on measurements of acoustic attenuation and sound speed at two frequencies, it synthesizes the entire frequency dependence of the complex effective specific heat of the gas, which is the macroscopic "footprint" of relaxation effects. The algorithm is based on the fact that for a simple relaxation process, such as occurs in many polyatomic gases at temperatures around 300 K, the effective specific heat traces a semicircle in the complex plane as a function of frequency. Knowing the high-frequency or instantaneous value of the specific heat provides the capability to not only sense the presence, but also infer the nature and, for mixtures of unlike-symmetry molecules, the concentration of foreign molecules leaking in a host gas.

Original languageEnglish (US)
Article number238301
JournalPhysical review letters
Volume94
Issue number23
DOIs
StatePublished - Jun 17 2005

ASJC Scopus subject areas

  • Physics and Astronomy(all)

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