Raman Spectroscopy on Free-Base Meso-tetra(4-pyridyl) Porphyrin under Conditions of Low Temperature and High Hydrostatic Pressure.

We present a Raman spectroscopy study of the vibrational properties of free-base meso-tetra(4-pyridyl) porphyrin polycrystals under various temperature and hydrostatic pressure conditions. The combination of experimental results and Density Functional Theory (DFT) calculations allows us to assign most of the observed Raman bands. The modifications in the Raman spectra when excited with 488 nm and 532 nm laser lights indicate that a resonance effect in the Qy band is taking place.

Spectroscopic properties and singlet oxygen production by the compound ethyl 3,12-dioxopyran[3,2-a]xanthone-2-carboxylate.

The steady state and time resolved experiments together with absorption and emission spectroscopies and quantum chemical calculations have been employed to investigate spectroscopic properties of a xanthone-type compound (ethyl 3,12-dioxopyran[3,2-a]xanthone-2-carboxylate). The spectroscopic data show good agreement with results obtained from quantum chemical calculations. Additionally, this compound shows expressive quantum efficiency for triplet population and a quantum efficiency of singlet oxygen generation very close to unity.