Chadwick Helen, Alexandrowicz Gil
Department of Chemistry, Faculty of Science and Engineering, Swansea University, Swansea SA2 8PP, UK.
Phys Chem Chem Phys. 2022 Jun 15;24(23):14198-14208. doi: 10.1039/d2cp01372j.
A new method to measure surface phonons with a molecular beam is presented. The method extends the principles of He spin-echo spectroscopy, to the more complex case of a molecular beam exchanging energy with the surface. Measurements are presented for inelastic scattering of D from a Cu(111) surface. Similarly to helium spin-echo, experiments can be performed along optimal tilted projections making it possible to resolve energy peaks with a high energy resolution which is not restricted by the spread of energies of the incident beam. Two analysis methods for these molecular spin echo experiments are presented. A classical approach, analogous to that used for helium spin-echo, explains the most dominant excitation peaks measured, whereas a semi-classical approach allows us to identify smaller peaks which are related to the complexity of the multiple spin-rotation states which exist for molecules.
提出了一种用分子束测量表面声子的新方法。该方法将氦自旋回波光谱学原理扩展到分子束与表面交换能量的更复杂情况。给出了D从Cu(111)表面非弹性散射的测量结果。与氦自旋回波类似，可以沿着最佳倾斜投影进行实验，从而能够以不受入射束能量展宽限制的高能量分辨率分辨能量峰。给出了这些分子自旋回波实验的两种分析方法。一种类似于用于氦自旋回波的经典方法，解释了所测量的最主要的激发峰，而一种半经典方法使我们能够识别与分子存在的多种自旋旋转状态的复杂性相关的较小峰。
