Temperature measurements from CN spectra in a laser-induced plasma

Experimental Study of the Transient Response of Bunsen Flame to Nanosecond Pulsed Discharges

“…6), the vibrational temperatures of CN radicals are rather high and fairly constant (around 9000 K) while the rotational temperatures grow up from 4400 K to about 8000 K. Similar temperatures were obtained from measurements of the CN spectra in laser-induced plasmas in Ref. [36], although in that case, no evidence of differences between rotational and vibrational temperatures was found. In this experiment, the growth of the rotational temperature manifests that the CN radicals may undergo an endothermic process with high initial vibrational energy in non-equilibrium plasma.…”

“…Similar to Refs. [31,35,36], the high temperature emission spectra of CN violet band in the plasma were recorded and analyzed. As shown in Fig.…”

CN and C2 vibrational spectra analysis in molecular LIBS of organic materials

“…The vibrational temperatures for CN violet and C 2 Swan bands systems were determined by a least-square fitting program NMT applying the Nelder-Mead algorithm, developed at the University of Tennessee Space Institute [35][36][37][38][39]. This program is used in producing theory spectra for the selected diatomic molecular transitions and wavelength regions.…”

Spectroscopy of laser-induced carbon plasma with nanosecond time resolution

“…The fitting process continues in steps until the error of the fit becomes smaller than a given limit. The least-squares process is carried out corresponding to the Nelder-Mead Temperature (NMT) algorithm [9], while the calculation of the theoretical spectrum is based on computed diatomic line-strength (Hönl-London) factors [10]. Time-averaged spectra, like the one above, are more intense and therefore have a better signal-to-noise ratio than time resolved spectra, to be discussed later.…”

“…(1) we used the 'Step and Glue' method to collect emission spectra time-slices at 80 ns intervals, using 532 nm laser radiation for plasma excitation. Each time-slice spectrum was fit to exact theoretical C 2 Swan band vibration-rotation intensities by means of the NMT (Nelder-Mead Temperature) algorithm to obtain a local thermal equilibrium vibration-rotation temperature estimate [9].…”