“…In summary, phonons, which are the COP in bismuth selenide, are responsible for generating the terahertz frequency, as mentioned in the TRUS section above. The terahertz spectroscopy directly validates the 2 THz frequency generation, while the TRUS was the initial method by which these oscillations were originally seen [14,18,26,30,32,34,36,37,[39][40][41][42][43][44][45][46][47][48][49][50][51][52][53] and was used to confirm the frequency of the 2 THz frequency. In addition, Prince Sharma et al in 2020 contrasted assessing the frequency determined through TRUS, revealing the COP oscillations [34,48] to evaluate the frequency from the kinetic spectrum.…”