| 概 要 |
This presentation will be focused on the investigation of the lowest electronic states and some of their properties in biradicals.
According to our findings, the so far rarely observed inverse heavy-atom effect could be in methylcarbenes achieved by changing the substituent. While bromo substitution of methylcarbene strengthens the spin-orbit coupling between S0 and T1 states, the presence of germyl group decreases SOC. According to our results, a decrease in SOC caused by
the germyl group could reduce the probability of both radiationless and radiative S0/T1 transitions. We ascribe the qualitatively different effect of the substituents to absence of the lone pairs of GeH3 group and we show that the contributions of heavy atoms are mainly caused by interactions of their p orbitals. Moreover, inverse heavy-atom effect seems to be additive and multiple substitutions may lead to its strong enhancement.
We further suggest new approach to possible measurement of the parity-violation effects in chiral molecules based on the electronic-energy shifts of the components of the lowest triplet of a biradical. It seems that the best candidates among systems studied for measurement are molecules with the –GaH–¨Bi⊕–Bi< fragment. There is high probability that these molecules would have triplet ground state and splitting of the parameter D of their lowest triplet due to parity violation is of the order of 104 Hz. Results support our presumption that the parity-violation effect on splitting of the triplet T1 should be dominated by its interactions with the close-lying singlet S0.
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