Design and performance of a new FT-ICR cell operating at a temperature range of 77-438 K

A new ion cell for Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS), which can be operated within the temperature range 77-438 K, has been designed and constructed. It has an elongated open-ended cylindrical configuration with capacitively coupled trapping electrodes. Fast and accurate thermal control of the cell is realized by embedding a heating element and a cooling pipe into the ceramic jacket holding the cell electrode plates. To determine the geometry factor, ß, of the cell a novel empirical methodology has been developed that is applicable to any ICR cell. This was achieved by comparing breakdown diagrams of protonated leucine enkephalin obtained using the new cell with those obtained using a well characterized cell. Energy-resolved collision-activated dissociation (CAD) of protonated leucine enkephalin, performed using the new cell, was applied to probe the internal energy content of ions at different ICR cell temperatures. These experiments demonstrate that the trapped ion population reaches the preset temperature of the cell through thermal equilibration with the cell walls by blackbody infrared radiation. This has permitted FT-ICR-MS studies (dissociation or ion-molecule reactions, etc.) to be performed at a wide temperature range, including low temperatures.

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