Diatomic molecules photoelectron spectroscopy

Unlike the stable molecule N2O, the sulfur analogue N2S decomposes above 160 K. In the vapour phase N2S has been detected by high-resolution mass spectrometry. The IR spectrum is dominated by a very strong band at 2040 cm [v(NN)]. The first ionization potential has been determined by photoelectron spectroscopy to be 10.6 eV. " These data indicate that N2S resembles diazomethane, CH2N2, rather than N2O. It decomposes to give N2 and diatomic sulfur, S2, and, hence, elemental sulfur, rather than monoatomic sulfur. Ab initio molecular orbital calculations of bond lengths and bond energies for linear N2S indicate that the resonance structure N =N -S is dominant. 

In the following, we will discuss a number of different adsorption systems that have been studied in particular using X-ray emission spectroscopy and valence band photoelectron spectroscopy coupled with DFT calculations. The systems are presented with a goal to obtain an overview of different interactions of adsorbates on surfaces. The main focus will be on bonding to transition metal surfaces, which is of relevance in many different applications in catalysis and electrochemistry. We have classified the interactions into five different groups with decreasing adsorption bond strength (1) radical chemisorption with a broken electron pair that is directly accessible for bond formation (2) interactions with unsaturated it electrons in diatomic molecules (3) interactions with unsaturated it electrons in hydrocarbons ... 

The major changes in the new edition are as follows There are three new chapters. Chapter 1 is a review and summary of aspects of quantum mechanics and electronic structure relevant to molecular spectroscopy. This chapter replaces the chapter on electronic structure of polyatomic molecules that was repeated from Volume I of Quantum Chemistry. Chapter 2 is a substantially expanded presentation of matrices. Previously, matrices were covered in the last chapter. The placement of matrices early in the book allows their use throughout the book in particular, the very tedious and involved treatment of normal vibrations has been replaced by a simpler and clearer treatment using matrices. Chapter 7 covers molecular electronic spectroscopy, and contains two new sections, one on electronic spectra of polyatomic molecules, and one on photoelectron spectroscopy, together with the section on electronic spectra of diatomic molecules from the previous edition. In addition to the new material on matrices, electronic spectra of polyatomic molecules, and photoelectron... 

The homonuclear diatomic molecules are the simplest closed set of molecules. Many of the electron affinities of the main group diatomic molecules have been measured by anion photoelectron spectroscopy (PES), but only a few have been confirmed. These Ea can be examined by their systematic variation in the Periodic Table. Calculating Morse potential energy curves for the anions and comparing them with curves for isoelectronic species confirm experimental values. The homo-nuclear diatomic anions of Group IA, IB, VI, VII, and 3d elements and NO are examined first. 

In conventional photoelectron spectroscopy, angular distributions are known to provide valuable insight into the underlying dynamics. A few groups have, moreover, recently reported measurements of angular distributions in pump-probe photoelectron spectra [332, 406]. Althorpe and Sei-deman have also examined the angular distributions of photoelectrons in the pump-probe ionization for a rigid diatomic molecule NO [8]. 

Ionization potentials of transient species have been measured by photoelectron spectroscopy and this technique may be sufficiently sensitive to be used for monitoring energy states of diatomic and perhaps polyatomic product molecules. Although quantitative energy disposal data have not been reported yet, the photoelectron spectroscopic method appears to be useful for diatomics which cannot be observed by conventional spectroscopic techniques. Like laser-induced fluorescence, the Franck-Condon factors of the ground state and the ion must be known to obtain vibrational populations from the intensity data. 

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