Influence of the length and position of the collision cell on the resolving power attainable from collisionally activated processes in sector instruments

The energy resolution in a high resolution tandem mass spectrometer was investigated in terms of the length and position of the central collision cell. Both these parameters have to be chosen carefully to eliminate collisional broadening phenomena that can severely limit the energy resolution in such instruments. A theory that describes collisional broadening, to first order, has been derived that accounts for the observed phenomena. It was found experimentally that collisional broadening can be reduced to less than 0.001 eV per kiloelectronvolt collision energy. Experimental data confirmed that only the size of the resolving slits and thermal broadening, due to the target gas, limited the ultimate energy resolution available.