Raman spectrometry was employed to study the characteristics of Raman spectra of polyethylene terephthalate (PET), which were treated with sodium hydroxide, sulfuric acid and copper sulfate, respectively. Raman spectra under different conditions were obtained and the characteristics of the Raman spectra were analyzed. The morphology structures were observed under different conditions using Atomic Force Microscope. The results show that the spectral intensity of PET treated with sodium hydroxide is higher than that untreated between 200-1750 cm-1, while the intensity of PET treated with sodium hydroxide is lower than that untreated beyond 1750 cm-1 and the fluorescence background of Raman spectra is decreased. The spectral intensity of PET treated with sulfuric acid is remarkably reduced than that untreated, and the intensity of PET treated with copper sulphate is much higher than that untreated.
In this work it is shown the benefit of using waveform integration of the avalanche pulses of MPPC for enhancing the photon number resolving capability of Multi-Pixel Photon Counter (MPPC). Up to 47 photon equivalent peaks can be distinguished in the Photon-Number-Resolving (PNR) spectrum with a repetition frequency of 80 MHz, which is the largest reported number obtained at room temperature as far as we know.