A comprehensive understanding of the phase transitions and physical properties of diatomic molecules under extreme pressures and temperatures is necessary. Utilizing a Doppler pin system and a multi-channel optical pyrometer, shock Hugoniot data and temperature states were obtained. First- and second-shock temperatures, ranging from 6000 K to 9000 K, were determined through spectral radiance analysis. The shock cooling phenomenon at second-shock against LiF was observed in each experiment, which established experimental reproducibility. The recorded radiance outputs were found in excellent order, resulting in precise shock temperatures and generating experimental uncertainties of less than 5%. Transformed velocity histories facilitated an accurate depiction of time-varying shock transmittance within compressed liquid and corroborated the book transparency of LiF under shock conditions. This work highlights the efficacy of combining interferometry and pyrometry for obtaining precise Hugoniot state temperatures and investigating shock cooling phenomena while accounting for LiF's melting behavior.