Investigation of CD effects in the multi photon ionisation of R-(+)-3-methylcyclopentanone

The circular dichroism (CD) in ion yield for different excitation/ionisation schemes for R-(+)-3-methylcyclopentanone was measured with circular dichroism laser mass spectrometry (CD-LAMS). We discovered a cumulative CD effect of successive electronic transitions, resulting in an enhancement of the CD in ion yield. Two photon excitation of the n–π∗-transition compared with the one photon process showed a vanishing CD effect.