Ventalon Cathie, Fraser James M, Vos Marten H, Alexandrou Antigoni, Martin Jean-Louis, Joffre Manuel
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.
Proc Natl Acad Sci U S A. 2004 Sep 7;101(36):13216-20. doi: 10.1073/pnas.0401844101. Epub 2004 Aug 19.
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.
我们展示了在中红外啁啾超短脉冲泵浦下，羧基血红蛋白的CO伸缩振动中的振动攀升现象。通过使用光谱分辨的泵浦-探测测量，我们直接观测到了由激发的振动布居数引起的诱导吸收线，直至v = 6。在某些情况下，我们还观测到了受激辐射，这为振动布居数反转提供了直接证据。本研究提供了强场 regime 中CO伸缩振动的重要光谱参数，例如直至v = 6到v = 7振动跃迁的跃迁频率和退相时间。我们测量到了等间距的振动跃迁，这与直至v = 6的莫尔斯势的能级相符。有趣的是，观测到差分吸收光谱的积分与假设偶极矩与键长呈线性依赖关系的简单一维莫尔斯模型所预期的结果相差甚远。
