title: Absolute measurement of femtosecond pump-probe signal strength.
abstract: The absolute femtosecond pump-probe signal strength of deprotonated fluorescein in basic methanol is measured. Calculations of the absolute pump-probe signal based on the steady-state absorption and emission spectrum that use only independently measured experimental parameters are carried out. The calculation of the pump-probe signal strength assumes the pump and probe fields are both weak and includes the following factors: the transverse spatial profile of the laser beams; the pulse spectra; attenuation of the propagating pulses with depth in the sample; the anisotropic transition probability for polarized light; and time-dependent electronic population relaxation. After vibrational and solvent relaxation are complete, the calculation matches the measurement to within 10% error without any adjustable parameters. This demonstrates quantitative measurement of absolute excited state population.
authors.affiliation: Department of Chemistry and Biochemistry, University of Colorado, Boulder, Colorado 80309-0215, USA.
authors.forename: Byungmoon
authors.initials: B
authors.lastname: Cho
authors.forename: Vivek
authors.initials: V
authors.lastname: Tiwari
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Hill
authors.forename: William K
authors.initials: WK
authors.lastname: Peters
authors.forename: Trevor L
authors.initials: TL
authors.lastname: Courtney
authors.forename: Austin P
authors.initials: AP
authors.lastname: Spencer
authors.forename: David M
authors.initials: DM
authors.lastname: Jonas