Supersonic cooling of short-lived molecular states in a pulsed microcavity plasma jet

microplasma;supersonic cooling;molecular spectroscopy

Su, Rui ; Eden ; James G.

关键词: microplasma;    supersonic cooling;    molecular spectroscopy;   

Others  :  https://www.ideals.illinois.edu/bitstream/handle/2142/90736/SU-THESIS-2016.pdf?sequence=1&isAllowed=y

美国|英语

来源: The Illinois Digital Environment for Access to Learning and Scholarship

【 摘 要 】

Electronic states of helium diners having potential energy > 24 eV and radiative lifetimes as short as 19 ns have been generated in a micro-plasma jet at super-atmospheric pressure and rotationally cooled by supersonic expansion. Spatial-temporal spectrograms of d^3Σ+u→(b^3)π_g (v', v") = (0, 0) emission are obtained, which contain the information about the dynamic cooling process during the molecular beam expansion. Analysis shows the spatial-temporal evolution of the rotational temperature to be a damped sinusoid that reaches a minimum value of 100 K, which is attributed to the reflection of electrons from a virtual cathode located downstream of the jet nozzle. Data fitting to the damped sinusoid function yields a spatially-averaged electron density of 10^8 cm^(-3).The experimental setup has the potential to be used in exploration of the spectroscopy and plasma dynamics in various gas molecules.