Rapid, broadband spectroscopic temperature measurement of CO2 using VIPA spectroscopy

TL;DR

This paper demonstrates a rapid, broadband spectroscopic method using VIPA spectroscopy combined with an optical frequency comb to measure CO2 temperature dynamics with high temporal and spectral resolution.

Contribution

It introduces a novel technique integrating VIPA spectroscopy with a supercontinuum laser for fast, broadband temperature measurements of CO2 in milliseconds.

Findings

Achieved spectral resolution of 0.075 cm-1 with 2 ms integration.

Measured temperature changes with 2.6 K resolution.

Validated spectroscopic temperatures against thermistor measurements.

Abstract

Time-resolved spectroscopic temperature measurements of a sealed carbon dioxide sample cell were realized with an optical frequency comb combined with a two-dimensional dispersive spectrometer. A supercontinuum laser source based on an erbium fiber mode-locked laser was employed to generate coherent light around 2000 nm (5000 cm-1). The laser was passed through a 12-cm long cell containing CO2, and the transmitted light was analyzed in a virtually imaged phased array- (VIPA-) based spectrometer. Broadband spectra spanning more than 100 cm-1 with a spectral resolution of roughly 0.075 cm-1 (2.2 GHz) were acquired with an integration period of 2 ms. The temperature of the CO2 sample was deduced from fitting a modeled spectrum to the line intensities of the experimentally acquired spectrum. Temperature dynamics on the time scale of milliseconds were observed with a temperature resolution of 2.6 K. The spectroscopically-deduced temperatures agreed with temperatures of the sample cell measured with a thermistor. Potential applications of this technique include quantitative measurement of carbon dioxide concentration and temperature dynamics in gas-phase chemical reactions (e.g., combustion), and plasma diagnostics.