EXTERNAL MAGNETIC-FIELD EFFECTS ON FLUORESCENCE PROPERTIES ACROSS THE PHOTODISSOCIATION THRESHOLD OF ACETALDEHYDE VAPOR

Fluorescence of acetaldehyde vapor is quenched by an external magnetic field. The efficiency of the magnetic quenching of fluorescence nearly monotonically increases with increasing excess vibrational energy above the S1 origin for excitation below the photodissociation threshold, which is located at 317.25 nm in CH3CHO, whereas the magnetic quenching abruptly becomes less efficient with increasing excess energy above the dissociation threshold. Thus, the magnetic field effects on fluorescence properties drastically change across the photodissociation threshold both in CH3CHO and CD3CDO.