Patent ID: 8390816

Claim:
A method for measuring total reflection light with a far ultraviolet attenuated total reflection probe, wherein penetration depth of evanescent waves of total reflection light is equal to or higher than 150 nm in far ultraviolet wavelength range, the penetration depth being dependent on wavelength of far ultraviolet light, refractive index of an object to be measured, refractive index of optical material of the probe and incident angle of the far ultraviolet light on an interface between the probe and the object, the method comprising: providing the attenuated total reflection probe made of an optical material selected so as to have the penetration depth equal to or higher than 150 nm in far ultraviolet wavelength range, to make the probe contact with the object to be measured at an interface between the probe and the object; making the far ultraviolet light incident on the interface, the light having a wavelength in the wavelength range and having incident angle larger than critical angle so as to have the penetration depth equal to or higher than 150 nm; and measuring the total reflection light from the interface, to determine absorbance of the object to be measured.