Most of the biologically important molecules are chiral molecules. However, those molecules are generally non-volatile and easily decomposed at high temperatures. To generate the biologically important molecules in the gas phase, we employ the electrospray ionization (ESI) technique. The molecular ions produced by ESI are stored in the QIT at ~10 K and irradiated by UV laser pulses for photodissociation. All of the ions inside the QIT are extracted out to the reflectron time-of-flight (reTOF) mass spectrometer by applying DC pulses on the endcaps of the QIT. The UV photodissociation (UVPD) spectra are obtained by monitoring photofragment ions as a function of the UV wavelength.

To obtain the circular dichroism spectra, the chiral ions in the QIT are irradiated by left-handed and right-handed circularly polarized laser pulses (LCP and RCP, respectively). The differences between the photofragment ion signals produced by LCP and RCP pulses are recorded as a function of the laser wavelength.