Electron Momentum Spectroscopy of the Frontier Orbitals of Chlorodifluoromethane

We report on the first measurement of the electron momentum distributions of the three outermost valence orbitals for chorodifluoromethane(CHF2Cl)by binary(e,2e) electron momentum spectroscopy.The experimental data are compared with Hartree-Fock and density functional theory(DFT) calculations employing 6-31G,6-311 G^** and AUG-cc-pVQZ basis sets.For the summed momentum distribution of 8α′ 5α″ 7α′ orbitals,the DFT/.AUG-cc-pVQZ calculation gives the best fit.A very large and diffuse basis set,AUG-cc-pVQZ,is employed in the calculations to approach the Hartree-Fock limit of the basis set,but the improvement of the calculation quality is little in comparison with that calculated with the 6-311 G^** basis set,This indicates that the 6-311 G^** basis set is nearly saturated for the calculations of these three orbitals of CHF2Cl,and it is unnecessary to employ a larger basis set in the calculations.