Biography of George C. Pimentel

New parallel software (P_Anhar) for anharmonic vibrational calculations: Application to (CH3Li)2

“…In the light of these results, we observe that there are no fundamental or overtones bands for the monomer near 530 and 1158 cm −1 . On the contrary, anharmonic results for the dimer are in better agreement with the experimental values, which again points to the presence of aggregates during the formation and experimental characterization of the monomer 7. Although there is no difficulty assigning bands in the [480–620] cm −1 window, analysis of the [1040–1210] cm −1 spectral window is more complex.…”

“…In 1967, Andrews proposed an experimental protocol that enabled him to characterize with near certainty monomeric methyllithium trapped in an argon matrix. To this day, this protocol remains the experimental reference 7. During the next 30 years, numerous theoretical studies were done on the nature of the CLi bond in the monomer as well as in aggregates (CH 3 Li) n ( n = 1, … 4), but no further experimental work was undertaken until 1996, where a new study, using microwave spectroscopy technique,45 reported an effective r 0 bond of monomeric CH 3 Li.…”

“…7 Second, no theoretical calculations, even at very high levels of theory,8, 9 could explain the experimental assignment for such a simple molecule. Third, it is well known that the CH 3 X (X = Li, Na, or K) compounds have a strong tendency to aggregate; therefore, even if the experimental protocol of Andrews et al in 1967 led those authors to think that monomeric methyllithium was the only species that was present in the Ar matrix, two recent theoretical studies8, 9 seem to show that a new characterization of this compound is needed, in a very low temperature matrix,7, 10–17 as well as in the gaseous phase 18. In a previous study carried out for (CH 3 Li) n ( n = 1, … 6), at the harmonic level,9 we showed that aggregates, at least the dimer, existed in the Ar matrix.…”

Low‐Energy Electronic Excitations of N‐Substituted Heteroacene Molecules: Matrix Isolation Spectroscopy in Concert with Quantum‐Chemical Calculations

“…Matrix isolation experiments were performed according to standard techniques in this form, which were first reported by Pimentel et al . and thereafter tremendously developed by Andrews et al . Details of the matrix setup in Heidelberg can be found elsewhere .…”

“…[54] Additionally,c ompound 2 was purified by recrystallisation from chloroform. Matrix isolation experiments were performed according to standard techniques in this form, which were first reported by Pimentel et al [41] and thereafter tremendously developed by Andrews et al [55][56][57][58] Details of the matrix setup in Heidelberg can be found elsewhere. [59] The substances were evaporated in aw ater-cooled Knudsen-type effusion cell containing ag raphite tube inside ac eramic unit surrounded by aT ah eating coil.…”