卤素双原子分子部分电子态的完全振动能谱和离解能

用代数方法(AM)可以获得双原子分子包含最高振动能级在内的所有高阶振动能级的完全振动能谱; 基于Leroy和Bernstein的能级表达式, 研究了卤族元素双原子分子Cl2-A’3∏(2u)、Br2-X1∑+g和I2-0+u电子态的完全振动能谱和离解能, 得到的理论结果与实验符合得很好.     

振动圆二色谱: 一种确定手性分子绝对构型的新方法

手性分子绝对构型的确定是一个极其重要且长期存在的问题. 振动圆二色谱是在红外波长区域测定分子圆二色性的一种新方法, 极大地扩展了圆二色谱的应用范围. 振动圆二色谱法通过构象搜索、量子化学计算等手段准确预测手性分子的振动圆二色谱图, 进而与实测谱图进行比较确定其绝对构型. 该方法已经得到了越来越广泛的应用, 必将成为一种有效测定手性分子绝对构型的常规方法.     

Elucidating the Structure of Chiral Molecules by using Amplified Vibrational Circular Dichroism: From Theory to Experimental Realization

Recent experimental observations of enhanced vibrational circular dichroism (VCD) in molecular systems with low‐lying electronically excited states suggest interesting new applications of VCD spectroscopy. The theory describing VCD enhancement through vibronic coupling schemes was derived by Nafie in 1983, but only recently experimental evidence of VCD amplification has demonstrated the extent to which this effect can be exploited as a structure elucidation tool to probe local structure. In this Concept paper, we give an overview of the physics behind vibrational circular dichroism, in particular the equations governing the VCD amplification effect, and review the latest experimental developments with a prospective view on the application of amplified VCD to locally probe biomolecular structure.     

Fluorescence Spectroscopy of Single Molecules under Ambient Conditions: Methodology and Technology

This review presents an overview of the fluorescence detection and spectroscopy of single molecules (SMS) in liquids and on surfaces under ambient conditions. The various techniques of SMS, such as confocal epifluorescence detection and wide‐field imaging are presented and discussed, together with the different methods of data analysis such as fluorescence correlation spectroscopy and burst‐by‐burst analysis. Selected applications of the various techniques in physics, chemistry, and biology are described.     

Spin Symmetry Requirements in Density Functional Theory: The Proper Way to Predict Magnetic Coupling Constants in Molecules and Solids

In this paper it is argued that the use of density functional theory (DFT) to solve the exact, non-relativistic, many-electron problem, for magnetic systems requires imposing space and spin symmetry constraints exactly in the same way as it is currently done in ab initio wave function theory. This strong statement is supported on pertinent calculations for selected systems representative of organic diradicals, molecular magnets and antiferromagnetic solids. These calculations include several wave function methods of increasing accuracy and different forms of the exchange- correlation functional. The comparisons of numerical results carried out always within the same standard Gaussian Type Orbital atomic basis set show that imposing or not the spin and space constraints (restricted or unrestricted formalisms) leads to contradictory results. Therefore, it appears that, in the case of the Heisenberg magnetic constant, the present exchange-correlation functionals may provide reasonable numerical results although for the wrong physical reasons thus evidencing the failure of the current DFT methods to properly describe magnetic systems.     

Quantum control spectroscopy of vibrational modes: Comparison of control scenarios for ground and excited states in β-carotene

Quantum control spectroscopy (QCS) is used as a tool to study, address selectively and enhance vibrational wavepacket motion in large solvated molecules. By contrasting the application of Fourier-limited and phase-modulated excitation on different electronic states, the interplay between the controllability of vibrational coherence and electronic resonance is revealed. We contrast control on electronic ground and excited state by introducing an additional pump beam prior to a DFWM-sequence (Pump-DFWM). Via phase modulation of this initial pump pulse, coherent control is extended to structural evolution on the vibrationally hot ground state (hot-S₀) and lowest lying excited state (S₁) of β-carotene. In an open loop setup, the control scenarios for these different electronic states are compared in their effectiveness and mechanism.     

ChemInform Abstract: Electronic and Geometric Structure and Vibrational Spectra of MoF3 and WF3 Molecules.

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