A Raman circular intensity differential (R-CID) spectrophotometer with use of a photon counting system was designed and constructed. The performance of the developed system was examined and compared with that of previous one using a lock-in amplifier by measuring the R-CID spectrum of
d-α-pinene. In the case of using the new system, it was shown that a normalized experimental quantity (Δ
z-value) for R-CID spectroscopy can be obtained. For the couplet in the 750-805cm
-1 region, the Δ
z value was found to be approximately 5X10
-3. It is suggested that the relation between the intensity as well as the sign, and the wavenumber of the corresponding Raman band may make the more detailed interpretation of R-CID spectra possible.
Furthermore, the exsistence of the second kind of artifacts, which occurred in using a sinusoidal modulation technique, was revealed from the fact that the signal intensity of the 840cm
-1 band was reduced extremely by decreasing the gate time in photon counting.
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