Internal Energy Transfer to Secondary Ions in Electrospray Droplet Impact/Secondary Ion Mass Spectrometry

Abstract

Charged droplets formed by atmospheric pressure electrospray are injected through an orifice into vacuum, which strike sample molecules deposited on a metal substrate. To investigate the energetics in electrospray droplet impact (EDI), 4-chlorobenzylpyridinium chloride salt was used as a thermometer molecule. The only fragmentation ion observed was the pyridinium ion. The internal energy distribution of the secondary molecular ion was estimated by the “Survival yield” method. It was revealed that 2.88 eV was transferred to the secondary ion as an internal energy by the impact of 10⁶ eV projectiles, [(H₂O)₉₀₀₀₀+100H]¹⁰⁰⁺.