Coherent vibrational climbing in carboxyhemoglobin.
We demonstrate vibrational climbing in the CO stretch of carboxyhemoglobin pumped by midinfrared chirped ultrashort pulses. By use of spectrally resolved pump-probe measurements, we directly observed the induced absorption lines caused by excited vibrational populations up to v = 6. In some cases, we also observed stimulated emission, providing direct evidence of vibrational population inversion. This study provides important spectroscopic parameters on the CO stretch in the strong-field regime, such as transition frequencies and dephasing times up to the v = 6 to v = 7 vibrational transition. We measured equally spaced vibrational transitions, in agreement with the energy levels of a Morse potential up to v = 6. It is interesting that the integral of the differential absorption spectra was observed to deviate far from zero, in contrast to what one would expect from a simple one-dimensional Morse model assuming a linear dependence of dipole moment with bond length.
Centre National de la Recherche Scientifique Unité Mixte de Recherche 7645, Institut National de la Santé et de la Recherche Médicale, Ecole Polytechnique-Ecole Nationale Supérieure de Techniques Avancées, Palaiseau, France.
Cathie
C
Ventalon
James M
JM
Fraser
Marten H
MH
Vos
Antigoni
A
Alexandrou
Jean-Louis
JL
Martin
Manuel
M
Joffre
D002263:Carboxyhemoglobin / Q000737:chemistry*; D013057:Spectrum Analysis; D014732:Vibration
D002263:Carboxyhemoglobin