Spectrum Vis-NIR absorption coefficient spectrum of CH4 phase-I crystal at 90 K Spectrum Vis-NIR absorption coefficient spectrum of CH4 phase-I crystal at 80 K Spectrum Vis-NIR absorption coefficient spectrum of CH4 phase-I crystal at 70 K Spectrum Vis-NIR absorption coefficient spectrum of CH4 phase-I crystal at 60 K Spectrum Vis-NIR absorption coefficient spectrum of CH4 phase-I crystal at 50 K Spectrum Vis-NIR absorption coefficient spectrum of CH4 phase-I crystal at 40 K Spectrum Vis-NIR absorption coefficient spectrum of CH4 phase-I crystal at 30 K