| 摘要 |
PURPOSE:To allow the measurement of a very small black sample or spherical (or particulate) sample which is difficult to be measured by obtaining the optoacoustic IR spectra corresponding to IR absorption spectra. CONSTITUTION:The sample is irradiated with the modulating IR light 1 stopped down by a condenser mirror 3 via a crystal plate 11 and the optoacoustic IR signal generated from the microsample (a) is detected by a high-sensitivity microphone 12 and is amplified by a preamplifier 13; thereafter, the signal is sent to a data processor 16. A piston 14 is moved by a step motor 15 and the volume in the hermetic space in a detector is gradually changed. The optoacoustic IR signal of the preamplifier 13 is fed back to a data processor 16 at all times so as to determine the position where the optoacoustic signal generated from the sample is increased by a resonance phenomenon. The pres sure in the detector S is monitored at all times by a pressure sensor built in a valve 20. The piston 14 is changed and the optoacoustic signal is subjected to Fourier transform by the data processor 16 in the position where the optoacoustic signal detected by the high-sensitivity microphone 12 is maximized. by which the optoacoustic IR spectra are obtd. |
