Time-resolved spectral investigation of low-temperature plasma induced in gas mixtures by laser-produced plasma or nanosecond pulses of extreme ultraviolet radiation

Abstract

The article presents comparative studies of low-temperature plasmas produced by two different experimental methods. In the first method [laser-produced plasma (LPP)-induced], low-temperature plasmas were created as a result of the interaction of laser-produced plasma (LPP) with ambient gas in the form of a gas mixture at low pressure surrounding the LPP. The LPP was produced by irradiating a gas puff target, formed from the same gas mixture, with an Nd:YAG laser pulse. In the second method [extreme ultraviolet (EUV)-induced], low-temperature plasmas were created by irradiating a small amount of a gas mixture, injected into a vacuum chamber, with a nanosecond pulse of extreme ultraviolet (EUV) radiation. The EUV pulses were generated using a laser plasma EUV source. Plasmas, created employing both methods, were investigated using time-resolved optical spectrometry. The results of measurements showed different time dependencies regarding emission lines and molecular bands, indicating differences in the processes leading to the formation of low-temperature plasmas. It has been shown that both methods produce CN molecular species; however, the emission times of the corresponding spectral bands differ significantly. It was found that these differences result from different mechanisms of atomic and molecular processes dominant in both methods of generating low-temperature plasma.