Department of Chemistry, University of California, Berkeley, California 94720, USA.
J Chem Phys. 2018 May 21;148(19):194303. doi: 10.1063/1.5027258.
The excited state relaxation dynamics of adenosine and adenosine monophosphate were studied at multiple excitation energies using femtosecond time-resolved photoelectron spectroscopy in a liquid water microjet. At pump energies of 4.69-4.97 eV, the lowest ππ excited state, S, was accessed and its decay dynamics were probed via ionization at 6.20 eV. By reversing the role of the pump and probe lasers, a higher-lying ππ state was excited at 6.20 eV and its time-evolving photoelectron spectrum was monitored at probe energies of 4.69-4.97 eV. The S ππ excited state was found to decay with a lifetime ranging from ∼210 to 250 fs in adenosine and ∼220 to 250 fs in adenosine monophosphate. This lifetime drops with increasing pump photon energy. Signal from the higher-lying ππ excited state decayed on a time scale of ∼320 fs and was measureable only in adenosine monophosphate.
使用飞秒时间分辨光电子能谱在液态水微射流中，在多个激发能量下研究了腺苷和单磷酸腺苷的激发态弛豫动力学。在 4.69-4.97 eV 的泵浦能量下，可获得最低的 ππ 激发态 S，并通过在 6.20 eV 处的电离来探测其衰减动力学。通过反转泵浦和探测激光的作用，在 6.20 eV 处激发了一个较高的 ππ 态，并在探测能量为 4.69-4.97 eV 时监测其时间演化光电子能谱。发现 S ππ 激发态在腺苷中的衰减寿命范围为约 210 至 250 fs，在单磷酸腺苷中的衰减寿命范围为约 220 至 250 fs。该寿命随泵浦光子能量的增加而降低。来自较高的 ππ 激发态的信号在约 320 fs 的时间尺度上衰减，仅在单磷酸腺苷中可测量。
