Kinetic energy of an N+ ion cloud throughout the stability diagram

A precise rime-of-flight method previously developed is used to investigate the average kinetic energy of an N+ ion cloud. From values obtained for di fferent points in the Mathieu stability diagram, variation of the kinetic e nergy versus the corresponding experimental parameters is estimated. It is observed that the magnitude depends essentially on the smallest two-dimensi onal component of the three-dimensional potential well. Measurements at dif ferent radiofrequencies (0.5, 1, and 1.5 MHz) show that the kinetic energy does not increase with the rf frequency. From the observed temporal variati on of the kinetic energy, collisional cooling is evidenced. (Int J Mass Spe ctrom 190/191 (1999) 37-45) (C) 1999 Elsevier Science B.V.