A comprehensive study of cold protonated tyramine: UV photodissociation experiments and ab initio calculations.

We present a comprehensive experimental study of protonated tyramine ions in a cold 3D quadrupole ion trap coupled to a time-of-flight mass spectrometer. Multiple UV photodissociation techniques have been developed, including single and double resonance spectroscopy along with time-resolved excited state lifetime measurements through a picosecond pump-probe scheme. An original UV-UV hole burning method is presented which can be used without modification of the quadrupole ion trap. The electronic spectrum of the cold protonated tyramine exhibits well-defined vibronic transitions, allowing the firm assignment of its two low-lying energy conformations by comparison with CC2 ab initio excited state calculations.