Double ionization potential similarity

The symmetry-correct anion orbitals can also be utilized in calculations of states of the N03 cation. The primary purpose of this work is to examine the NO3 ionization spectrum and the ground and low excited states of the N03 cation system by the DIP-STEOM-CCSD method (40) (double ionization potential similarity transformed equation-of-motion coupled-cluster singles and doubles). The DIP-STEOM-CCSD method is built upon the IP-EOM-CCSD method (32) (ionization potential equation-of-motion coupled-cluster singles and doubles), which in turn, has been shown to be equivalent (41,42) to singly ionized FSMRCC, such as the example of Kaldor above. The DIP-STEOM-CCSD method generates ground and excited states of the cation by deletion of... 

The structure of the p-p propagator is very similar to that of G. This popagator describes the simultaneous annihilation of two electrons from the system as well as the simultaneous attachment of two electrons to the system. In particular, the pole positions of the first and second part of FI represent double ionization potentials (DIP) and double attachment energies. DIPs, EAs, and IPs are, of course, important quantities of electronic systems. But not only the pole positions are related to experiment. The residue amplitudes and contain relevant information on the single and double ionization and attachment (or scattering) processes. For instance, the partial-channel photoionization cross section for production of molecular ions in the nth state reads in the sudden approximation ... 

Spectroscopy.—The ionization potentials of thioketen (79) have been measured by means of photoelectron spectroscopy and found to be 8.52, 8.67, and 11.14 eV. The structure of thioketen (87) has been studied by X-ray crystallography, and it was found that the length of the carbon-carbon double bond is similar to that in the corresponding oxygen analogue. ... 

Another interesting observation in this study is that, while the dihydronaphthalene derivative 47 and the nitriles 53a, 53b, and 54 are formed from radical-cations centered in the CN double bond, the dihydroquinoline 50 results from a radical-cation centered in the alkene unit. These observations are in agreement with similar results obtained in the study of the photochemical reactivity of 2-aza-1,4-dienes under SET-sensitized conditions and suggest that two different radical-cations intermediates can be generated from functional groups with different ionization potentials. 

The EOM-CCSD method has been shown to be an accurate approach for calculating excitation energies (EE-) (29,30), electron affinities (EA-) (31), and ionization potentials (IP-) (32) of closed-shell systems. For the computations presented here, a coupled-cluster singles and doubles (CCSD) calculation is first performed on the closed-shell NO3" anion system. The Hamiltonian is similarity... 

The dwelltime of ions within the ion source is defined by the extraction voltages applied to accelerate and focus them into an ion beam and by the dimensions of that ion source. In standard El ion sources the freshly formed ions dwell about 1 ps before they are forced to leave the ionization volume by action of the accelerating potential. [41] As the ions then travel at speeds of some 10 m s they pass the mass analyzer in the order of 10-50 ps (Fig. 2.9). [9] Even though this illustration has been adapted for a double focusing magnetic sector mass spectrometer, an ion of m/z 100, and an acceleration voltage of 8 kV, the effective time scales for other types of instruments (quadrupole, time-of-flight) are very similar under their typical conditions of operation (Table 2.4). 

---