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We present the polarized reflection spectra of several MPcs (M≡Co, Ni, Cu, Zn, Pb) in the Q-band region and interpret them based on conventional exciton theory. We compare the polarized reflection spectra of the phthalocyanine radical salts NiPc(AsF₆)_0.5, H₂Pc(AsF₆)_0.67 and LiPc and interpret the new absorption band near the Q-band using the relationship between the degree of oxidation and the intensity of this new band. Based on the pressure dependence of this new band and the diagnostic phonon modes, we prove a pressure-induced charge transfer in NiPc(AsF₆)_0.5. A metal–insulator phase transition is predicted from the analysis of the plasmon absorption and is confirmed by the high-pressure electrical resistivity. We propose the origin of the pressure-induced charge transfer and the mechanism of the metal–insulator transition. We find the optical transition associated with the 3d_z2 band in the reflection spectrum of CoPc(AsF₆)_0.5, which is proved by comparison with the mixed crystals Co_xNi_{1 − x}Pc(AsF₆)_0.5. A new weak intermolecular optical transition is found through the resonance enhancement of a local phonon in the mixed crystals Co_xNi_{1 − x}Pc(AsF₆)_0.5.

Noninvasive glucose monitoring development is critical for diabetic patient continuous monitoring. However, almost all the available devices are invasive and painful. Noninvasive methods such as using spectroscopy have shown some good results. Unfortunately, the drawback was that the tungsten halogen lamps usage that is impractical if applied on human skin. This paper compared the light emitting diode (LED) to traditional tungsten halogen lamps as light source for glucose detection where the type of light source plays an important role in achieving a good spectrum quality. Glucose concentration measurement has been developed as part of noninvasive technique using optical spectroscopy. Small change and overlapping in tungsten halogen results need to replace it with a more convenient light source such as LED. Based on the result obtained, the performance of LED for absorbance spectrum gives a significantly different and is directly proportional to the glucose concentration. The result shows a linear trend and successfully detects lowest at 60 to 160 mg/dL glucose concentration.