Coherent anti-Stokes Raman scattering from aligned nitrogen molecules

回転制御した窒素分子のラマン散乱分光

吉田 芙美子; 横山 啓一  

Yoshida, Fumiko; Yokoyama, Keiichi

Molecules are aligned by rotational coherence created with short laser pulses. Then, aligned molecules lose their coherence through the collision. The de-coherence rate is often measured by the decay of the coherent signal, such as four-wave mixing and orientation-dependent ionization. However, all these measurements give information only on the coherent state, i.e., off-diagonal elements of the density matrix. To understand the decoherence process completely, information both on the coherent and incoherent states is required, i.e., whole density matrix including diagonal elements. Therefore, it is worthwhile to develop a technique for measuring both the off-diagonal and diagonal elements simultaneously. As a candidate of such a technique, we explore the potential of the time-resolved vibrational coherent anti-Stokes Raman scattering (CARS) spectroscopy of aligned molecules.