Development of Molecular Beam Double Resonance Spectroscopy by Use of Evanescent Wave and Study of Molecule-Solid Surface Interactions

倏逝波分子束双共振光谱学的发展及分子-固体表面相互作用的研究

• 批准号: 02452083
• 负责人: SHIMIZU Tadao
• 金额: $ 4.42万
• 依托单位: University of Tokyo
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for General Scientific Research (B)
• 财政年份: 1990
• 资助国家: 日本
• 起止时间: 1990 至 1991
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-02452083/
• 关键词: evanescent wave spectroscopy; molecule scattering by the solid; supersonic molecular beam; double resonance spectroscopy; laser Stark spectroscopy; ammonia molecule; dipole transition

We have carried out molecular beam spectroscopy and evanescent wave spectroscopy to study interactions between solid surface and molecules in the gas phase.Combination of the supersonic molecular beam technique and the infrared double resonance spectroscopy enables measurements of the probability of collision induced transitions between specific vibration-rotation states of molecules. First, the molecular beam double resonance method was tested In the measurement of the state-to-state cross section of the rotational transitions in NH_3 caused by the dipole-quadrupole interaction with nonpolar target molecules. Our experimental procedure has been justified because the obtained cross sections agree quite well with those nonempirically calculated from a collision theory.Then, we applied the method to observe collision-induced population change in the rotational states of NH_3 scattered from solid surfaces, such as glass, Al, and Au. It has been found that the selection rule in the dipole transition dominates the collision induced transition on glass surface. On the other hand, the molecule makes a hard collision with metal surfaces, and there is no definite selection rule.Simultaneously, we have developed a evanescent-wave laser spectrometer, and detected rotation-vibration spectra of NH_3 molecules close to NaCl surface. The spectral line of NH_3 near the surface was broadened approximately by 50 %, compared with that in the gas phase. The line width was proportional to the square root of the surface temperature. This may be attributed to the phase relaxation induced by the interaction with the solid surface.In the future, we are going to combine the molecular beam method with the evanescent wave spectroscopy for further research of the scattering process on solid surface.

我们利用分子束光谱和倏逝波光谱研究了固体表面与气相分子之间的相互作用。超声波分子束技术和红外双共振光谱技术的结合，可以测量分子特定振动-旋转状态之间碰撞诱导跃迁的概率。首先，采用分子束双共振方法测量了偶极子-四极子与非极性靶分子相互作用引起的NH_3中转动跃迁的态-态截面。我们的实验过程是合理的，因为得到的截面与从碰撞理论非经验计算的截面相当吻合。然后，我们应用该方法观察了从固体表面（如玻璃、Al和Au）散射的NH_3在碰撞诱导下的旋转态的居群变化。发现偶极子跃迁中的选择规律支配着玻璃表面的碰撞诱导跃迁。另一方面，分子与金属表面发生硬碰撞，没有明确的选择规则。同时，我们研制了一种倏逝波激光光谱仪，检测了NaCl表面附近NH_3分子的旋转振动谱。表面附近NH_3的谱线较气相的谱线展宽约50%。线宽与表面温度的平方根成正比。这可能是由于与固体表面相互作用引起的相松弛。未来，我们将把分子束方法与倏逝波光谱相结合，进一步研究固体表面的散射过程。

项目成果

Y.Tanaka: "EvanescentーWave Spectroscopy of NH_3 Molecules near NaCl Surface" to be submitted to J.Chem,Phys.

Y.Tanaka：“NH_3 分子在 NaCl 表面附近的倏逝波光谱”将提交给 J.Chem,Phys。

Y.Tanaka: "Abnormal Rotational Energy Distribution in Cooling Process of NH_3 Supersonic Molecular Beam" to be submitted to J.Chem.Phys.

Y.Tanaka：“NH_3超音速分子束冷却过程中的异常旋转能量分布”即将提交给J.Chem.Phys。

Y.Tanaka: "Nonequilibrium rotational energy distribution in NH_3 supersonic molecular beam" Jpn.J.Appl.Phys.31. (1992)

Y.Tanaka：“NH_3超音速分子束中的非平衡旋转能量分布”Jpn.J.Appl.Phys.31。

Y.Tanaka: "Cooling Process of Rotational Degree of Freedom in Supersonic Molecular Beam" submitted for Presentation in Tenth International Conference on Laser Spectroscopy.

Y.Tanaka：“超音速分子束旋转自由度的冷却过程”提交第十届国际激光光谱会议上发表。

Y.Uematsu: "State-to-state cross section of rotational transition caused by dipole-quadrupole interaction between NH_3 and nonpolar molecules" J.Chem.Phys.96. (1992)

Y.Uematsu：“NH_3 和非极性分子之间的偶极-四极相互作用引起的旋转转变的状态到状态横截面”J.Chem.Phys.96。