Fluorescence-based method for determining the number of ions trapped in a FT-ICR mass spectrometer

A novel technique for determining the number of ions trapped inside a FT-ICR mass spectrometer is proposed. This technique is based on the detection of the spectral power radiated by fluorescing ions trapped inside the mass spectrometer. A pre-calibrated tungsten lamp was used to perform a calibration of the optical system. Using the absolute values of the energy radiated during an experiment, the number of ions trapped inside the cell was estimated. As reference ions, cations of rhodamine 6G and rhodamine B, whose gas-phase properties have been thoroughly studied, were chosen. The rhodamines have very high absorbance and high quantum yield in the gas phase. The method developed was compared to a previously published technique based on induced current measurements. A good agreement between the two techniques was found.

Graphical abstractFigure optionsDownload full-size imageDownload high-quality image (111 K)Download as PowerPoint slideHighlights► A novel technique determines the number of ions in an FTICR mass spectrometer. ► It is based on measuring the spectral power radiated by fluorescing trapped ions. ► A calibration for the absolute energy radiated was established. ► Trapped rhodamine 6G and rhodamine B ions were studied.