Steady-state absorption spectroscopy,circular dichroism,and resonance Raman spectroscopy have been used to investigate the thermal stability of LH2 complex isolated from purple photosynthetic bacterium Rps.palustris.The results show that:1)upon increasing the temperature,a transition from B800 and B850 to free bacteriochlorophyll(B780)happens;2)a gradual decrease and disappearance of CD signal in visible region occur;3)a shift of the frequency,belonging to C==C and C—C stretching vibration,to higher wavenumber takes place.It is suggested that LH2 complex can be dissociated in the presence of B800,B850 and carotenoids simultaneously.Single-exponential fitting on the dynamic decay curves gives the apparent time constants of hundreds of minutes for various pigments.
Sub-microsecond time-resolved absorption spectroscopy has been used to study the electronically excited state behavior of soluble multiwalled carbon nanotube (MWNTsCON((CH2)9- CH3)2, denoted as MDDA) in chloroform, toluene and cyclohexane. Following pulsed photo-excitation of MDDA at 355 nm, three major spectral components are clearly identified with the help of global analysis carried out over 7 representative kinetics curves from 450 to 700 nm. The solvent depend-ence of decay associated difference spectra (DADS) and the corresponding lifetimes help to assign these transient species to singlet state (S1), triplet state (T1) and charge-separated state (CS), re-spectively. Preliminary discussion had been made to explore the involved photophysical and electron transfer processes.
