Energy-sensitive cryogenic detectors for high-mass biomolecule mass spectrometry

Energy-sensitive calorimetric detectors that operate at low temperatures (" cryogenic detectors") have recently been applied for the first time as ion detectors in time-of-flight mass spectrometry Compared to conventional ioni zation-based detectors, which rely on secondary electron formation or the c harge created in a semiconductor, cryogenic detectors measure low-energy so lid stare excitations created by a particle impact This energy sensitivity of cryogenic defectors results in several potential advantages for TOF-MS. Cryogenic detectors are expected to have near 100% efficiency even for very large, slow-moving molecules, in contrast to microchannel plates whose eff iciency dregs considerably at large mass. Thus, cryogenic detectors could c ontribute to extending the mass range accessible by TOF-MS and help improvi ng detection limits. In addition, the energy resolution provided by cryogen ic detectors carl be used for charge discrimination and studies of ion frag mentation. ion-detector interaction, and internal energies of large molecul ar ions. Cryogenic detectors could therefore prove to be a valuable diagnos tic tool in TOF-MS. Here, we give a general introduction to the cryogenic d etector types most applicable to TOF-MS including those types already used in several TOF-MS experiments. We review and compare the results of these e xperiments, discuss practical aspects of operating cryogenic detectors in T OF-MS systems, and describe potential near future improvements of cryogenic detectors for applications in mass spectrometry: (C) 1999 John Wiley & Son s, Inc.