Ultrafast time-resolved absorption spectroscopy of geometric isomers of xanthophylls

作者：Niedzwiedzki Dariusz M; Enriquez Miriam M; LaFountain Amy M; Frank Harry A^*

来源：Chemical Physics, 2010, 373(1-2): 80-89.

DOI：10.1016/j.chemphys.2010.01.019

• Excited state energy
• Ultrafast transient absorption
• Xanthophylls
• Geometric isomers
• Excited state lifetime

This paper presents an ultrafast optical spectroscopic investigation of the excited state energies, lifetimes and spectra of specific geometric isomers of neoxanthin, violaxanthin, lutein, and zeaxanthin. All-trans- and 15,15'-cis-beta-carotene were also examined. The spectroscopy was done on molecules purified by HPLC frozen immediately to inhibit isomerization. The spectra were taken at 77 K to maintain the configurations and to provide better spectral resolution than seen at room temperature. The kinetics reveal that for all of the molecules except neoxanthin, the S-1 state lifetime of the cis isomers is shorter than that of the all-trans isomers. The S-1 excited state energies of all the isomers were determined by recording S-1 -> S-2 transient absorption spectra. The results obtained in this manner at cryogenic temperatures provide an unprecedented level of precision in the measurement of the S-1 energies of these xanthophylls, which are critical components in light-harvesting pigment-protein complexes of green plants.

• 出版日期2010-7-19