Photoelectron spectrum of water

Figure 5.13 The photoelectron spectrum of water vapour ionizations from the 1b, 3a, and 1b2 orbitals are indicated. Ionizations from the more stable 2a, orbital are not produced by the helium radiation used...

R. Sankari, M. Ehara, H. Nakatsuji, Y. Senba, K. Hosokawa, H. Yoshida, A. De Fanis, Y. Tamenori, S. Aksela, K. Ueda, Vibrationally resolved O Is photoelectron spectrum of water, Chem. Phys. Lett. 380 (2003) 647. 

Figure 24.30 The He I photoelectron spectrum of water. (From J. W. Rabelais, Principles of Ultraviolet Photoelectron Spectroscopy. New York Wiley, 1977).

Photoelectron spectrum of water. The inserts for the 2ai and 1i)2 levels have been magnified several times. The ionization potential for the 1ai molecular orbital is at 32.2 eV. 

Each of the occupied MOs contains two electrons, whereas the antibonding MOs of higher energy (4a, 2b2) are empty (Figure 1.1a). The photoelectronic spectrum of water, obtained via UV excitation with the He(l) line of helium (21.2eV), shows the bonding nature of the lb2 and 3a, MOs (presence of fine vibrational structure), whereas the b, MO is strictly non-bonding owing to symmetry limitations (Ij. 

Experimental confirmation of the order of MO energies for the water molecule is given by its photoelectron spectrum. Figure 5.13 shows the helium-line photoelectron spectrum of the water molecule. There are three ionizations at 1216, 1322 and 1660 kJ mol1. A fourth ionization at 3107 kJ mol-1 has been measured by using suitable X-ray photons instead of the helium emission. That there are the four ionization energies is consistent with expectations from the MO levels for a bent C molecule (see Figure 5.12). 

Fig. 4. Photoelectron spectrum of O(ls) for water vapor irradiated by the A1X line. To left of the main peak are the satellites. Solid line, experimental data vertical lines, results of calculations.53 The energy is counted from the main peak corresponding to ejection of I s electrons.

Copper(I) acetate is a white solid that slowly decomposes in air and is very unstable toward water. The green decomposition product has the molecular formula Cu2(CH3COO)2(OH)2. The far infrared spectrum of copper(I) acetate has bands at 230(s), 255 (s), 375(m), and 419(m) cm 1 that are distinct from those of starting material and decomposition product. The Cu 2Pi/2)3/2 band in the photoelectron spectrum of pure copper (I) acetate exhibits no secondary structure, in contrast to that of copper(II) acetate and the green decomposition product. 

Appelman has reviewed the case history of HOF, the recently isolated non-existent molecule, which may well be the reactive species formed when F2 reacts with water. The photoelectron spectrum of this unstable compound has been obtained by Berkowitz et al using He I resonance radiation. Three bands were observed which could be interpreted by analogy with the diatomic halogens and with the recently reported CIF. The first (adiabatic) ionization potential was found to be 12.69 0.03 eV, in close agreement with the photoionization value of 12.7 0.01 eV. 

Figure 4.8. XPS wide-scan spectrum of a Rh/AIjO, model catalyst prepared by impregnating AI2O3 with a solution of RhClj in water. The photoelectron and Auger peaks (left) are given, along with a region of interest from the Rh 3d spectrum of the fresh and the...

Fig. 3.3 X-ray photoelectron spectroscopy (XPS) spectrum of a Rh/Al203 model catalyst prepared by impregnating a thin film of AI2O3 on aluminum with a solution of RhCI3 in water. (Figure courtesy of L.C.A. van den Oetelaar, Eindhoven).

Pyrazine forms an azeotrope with water [60% pyrazine-40% water, b.p. 95.5° (uncorr.) (760mmHg) /ip 1.4510] (578). A method of assay for pyrazine and some common impurities has been developed (579). The dipole moment (Debye units) of pyrazine has been determined in dioxane, cyclohexane, and benzene as zero (580, cf. 581) and it has also been calculated as zero (133, 582). The e.s.r. spectrum (583) and the polarized single-crystal absorption spectra of pyrazine (and tetramethylpyrazine) (584) have been recorded. The photoelectron spectra of pyrazine and tetramethylpyrazine have been determined and suggest a different behavior towards electrophilic attack in the two cases (585). 

The HBO ion has been detected mass spectrometrically by Sholette and Porter (2.) and Farber and Frisch (2). However, no appearance potential data have been reported for the ion. Kroto et al. ( ) recently attempted to measure the photelectron spectrum of HBO by passing water vapor over heated boron. The spectrum showed no bands which could be definitely assigned to HBO monomer. Unfortunately, the region of their spectrum ( 14-15 eV) where the first photoelectron band of HBO would be expected to lie shows a broad band which also appeared In the spectrum of HBS above 1150"C. Kroto et al. 4) have assigned this band to dlborane. He believe the HBO band may well be hidden under this broad band. 

Instead of analyzing the photoelectron spectrum for fixed energy one may study the dependence of the full spectrum on the delay time. The result is shown in Figure 7 (left panel) which contains P E, T) as a function of energy E and delay-time T for water and its isotopes. 

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