Picosecond events in the photochemical cycle of the light-driven chloride-pump halorhodopsin

The early events in halorhodopsin after light excitation are
studied with picosecond time resolution. Absorption and
fluorescence measurements show that the electronically excited
state of the incorporated retinal has a lifetime of 5 ps. Within
that time a red-shifted photoproduct is formed that remains stable
for at least 2 ns.