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Full-Text Articles in Physical Sciences and Mathematics

Photothermal Lens Aberration Effects In Two Laser Thermal Lens Spectrometry, Stephen E. Bialkowski Jan 1985

Photothermal Lens Aberration Effects In Two Laser Thermal Lens Spectrometry, Stephen E. Bialkowski

Stephen E. Bialkowski

A comparison of theories describing two laser photothermal lens signals is given. The aberrant nature of this lens is accounted for in a theory which treats the propagation of a monitor laser in terms of a phase shift in this laser beam wave front. The difference between theories are discussed in terms of the predicted signal strengths and temporal behavior. The aberrant theory results in smaller theoretical signal strengths and different functional relationships between signal and analyte level.


Comparison Of Proton Transfers In (S2h5)+ And (O2h5)+, L. Bigham, Steve Scheiner Jan 1985

Comparison Of Proton Transfers In (S2h5)+ And (O2h5)+, L. Bigham, Steve Scheiner

Chemistry and Biochemistry Faculty Publications

The energetics and electronic rearrangements associated with proton transfer between S atoms in (H2S–H–SH2)+ are calculated using ab initio molecular orbital methods and compared with similar data in the first‐row analog (H2O–H–OH2)+. The full potential energy surface of (S2H5)+, calculated as a function of the H‐bond length as well as the position of the proton, contains two equivalent minima separated by a small energy barrier, whereas the surface of (O2H5)+ contains a single minimum corresponding to a symmetric …


Influence Of Basis Set On The Calculated Properties Of (H3n–Hcl), Z. Latajka, Steve Scheiner Jan 1985

Influence Of Basis Set On The Calculated Properties Of (H3n–Hcl), Z. Latajka, Steve Scheiner

Chemistry and Biochemistry Faculty Publications

The structure of (H3N–HCl) is investigated by ab initio calculations using a number of different basis sets ranging from minimal to split valence. The effects of including a diffuse sp shell and d orbitals on Cl are considered as well. The geometries of the complex and the isolated subunits are fully optimized. Minimal basis sets (STO‐3G, STO‐6G, and MINI‐1) lead to an overestimate of the interaction between the subunits. Addition of d functions produces only a marginal improvement. The 3‐21G, 3‐21+G, MIDI‐1, and LP‐31G split‐valence sets erroneously predict an ion pair …


Contribution Of Dispersion To The Properties Of H2s‐‐Hf And H2s‐‐Hcl, M. M. Szczesniak, Steve Scheiner Jan 1985

Contribution Of Dispersion To The Properties Of H2s‐‐Hf And H2s‐‐Hcl, M. M. Szczesniak, Steve Scheiner

Chemistry and Biochemistry Faculty Publications

Ab initio calculations are carried out using a doubly polarized basis set. Dispersion, evaluated by second‐order Møller–Plesset perturbation theory (MP2), is found to have a profound influence on the stabilities and structures of the H‐bonded complexes. The contribution of dispersion to the H‐bond energies of H2S‐‐HF and H2S‐‐HCl is 44% and 69%, respectively, placing this attractive term second in magnitude only to electrostatics. Reductions of the intermolecular distance of 0.17 and 0.34 Å result from inclusion of correlation effects. Nevertheless, the influence of dispersion upon the angular characteristics of the …