TITLE:
Ultrafast Laser Energy Density and Retinal Absorption Cross-Section Determination by Saturable Absorption Measurements
AUTHORS:
Alfons Penzkofer, Meike Luck, Tilo Mathes, Peter Hegemann
KEYWORDS:
Laser Pulse Peak Energy Density Determination; Ground-State Absorption Cross-Section Determination; Excited-State Absorption Cross-Section Determination; Saturable Absorption; ADS084BE Dye; Histidine Kinase Rhodopsin HKR1; Retinal Schiff Base RetA Cofactor; Number Density Determination
JOURNAL NAME:
Journal of Analytical Sciences, Methods and Instrumentation,
Vol.4 No.1,
March
26,
2014
ABSTRACT: Laser pulse nonlinear transmission
measurements through saturable absorbers of known absorption parameters allow
the measurement of their energy density. On the other hand, nonlinear transmission
measurements of laser pulses of known energy density through absorbing media allow
their absorption parameter determination. The peak energy density w0P of second harmonic pulses
of a mode-locked titanium sapphire laser at wavelength λP = 400 nm is determined by nonlinear energy transmission measurement TE through the dye ADS084BE
(1,4-bis(9-ethyl-3-car-bazovinylene)-2-methoxy-5-(2’-ethyl-hexyloxy)-benzene) in tetrahydrofuran. TE(w0P)
calibration curves are calculated for laser pulse peak energy density reading w0P from measured pulse
energy transmissions TE. The
ground-state absorption cross-section σP and the excited-state absorption cross-section σex at λP,
and the number density N0 of the retinal Schiff base isoform RetA in pH 7.4 buffer of the blue-light
adapted recombinant rhodopsin fragment of the histidine kinase rhodopsin HKR1
from Chlamydomonas reinhardtii were
determined by picosecond titanium sapphire second harmonic laser pulse energy
transmission measurement TE through RetA as a function of laser input peak energy density w0P. The complete absorption
cross-section spectrum σ