MXene-coated quartz tuning fork for sensitive light-induced thermoelastic spectroscopy

This paper demonstrates a customized quartz tuning fork (QTF) coated with the titanium carbide (Ti₃C₂T_x) MXene film that can effectively enhance the sensitivity of light-induced thermoelastic spectroscopy (LITES). The MXene film is coated at the root of the customized QTF. The film area is proven to have little impact on resonance frequency, bandwidth, quality factor, and amplitude of the second harmonic signal (2<i>f</i>) based on the fundamental flexural mode. With an optimum film thickness of 1.9 µm, the signal-to-noise ratio (SNR) of the light-induced thermoelastic signal is enhanced up to 8.7 times. A similar enhancement of 2<i>f</i> signals was observed at the overtone frequency. Despite the higher quality factor, the SNR of the 2<i>f</i> signal inspired at the overtone frequency is much lower than that of the 2<i>f</i> signal inspired at the fundamental frequency. Moreover, similar experimental results are observed on the commercial QTF coated with MXene film. The absorption coefficient from 1260 nm to 1680 nm of the MXene film is measured to be larger than 92%. Hence, the MXene film enables a promising application prospect for the LITES system in multiple gas measurements.