HeI photoelectron spectroscopic study on the electronic structure of the (CH3CH2)2N neutral radical

A continuous diethylamino (CH3CH2)2N radical beam is produced by pyrolysis of diethylnitrosamine (CH3CH2)2NNO at 725(±0.5)°C in a double-chamber UPS machine. The HeI photoelectron spectrum (PES) of (CH3CH2)2N is recorded. A sharp peak with the lowest ionization energy at 8.56±0.02 eV is assigned to the HOMO(3b2) of (CH3CH2)2N. The second band is overlapped with the first band of the NO species and centered near 9.82 eV; it comes from ionization of the 9a1 bonding orbital of (CH3CH2)2N. To assign the PES bands of (CH3CH2)2N, an improved density functional theory calculation based on the Amsterdam density functional (ADF) program package has been performed in C2v symmetry for the ground state of (CH3CH2)2N and for the equilibrium geometries of several states of the cation. The pyrolysis mechanism is (CH3CH2)2NNO→725±0.5°C(CH3CH2)2N+NO .