The circular dichroism from
22 steroidal 4-en-3-ones in cyclohexane solution has been recorded through the
wavelength range 400-265 nm. It is shown that both the singlet-triplet and the
singlet-singlet n → π* electronic transitions contribute. Through
examination of evidence from c.d. and X-ray structure analysis, it is concluded
that the conformation of the chromophore and its immediate environment remains
constant under the conditions of measurement. In three of the 6β- substituted
compounds the normal, highly structured, negative Cotton effect from the
singlet-singlet n → π* transition is modified by positive c.d. with
the same vibrational structuring. The origin of the positive contribution is
discussed.
Soft x-ray absorption spectroscopy and magnetic circular dichroism as operando probes of complex oxide electrolyte gate transistors