Abstract: An ICR cell (01) operates with a duplexer (08), which is an integral part of a transmission and receiving device (09) of an FT-ICR mass spectrometry device. The device transmits a transmitter (03) voltage to at least one electrode (11) of the ICR cell during an ion excitation phase and protects a preamplifier (04) from overvoltage. An ion received signal passes through a reception path (12) to the preamplifier during an ion detection phase. The duplexer has at least one active serial switch (07) with two switchable states, each with different series impedances, which is inserted in the reception path (12). As a result, a duplexer for an ICR cell of an FT-ICR mass spectrometry device is provided in which at least one electrode can be used for both ion excitation and for subsequent ion detection.

Abstract: An ICR cell (01) operates with a duplexer (08), which is an integral part of a transmission and receiving device (09) of an FT-ICR mass spectrometry device. The device transmits a transmitter (03) voltage to at least one electrode (11) of the ICR cell during an ion excitation phase and protects a preamplifier (04) from overvoltage. An ion received signal passes through a reception path (12) to the preamplifier during an ion detection phase. The duplexer has at least one active serial switch (07) with two switchable states, each with different series impedances, which is inserted in the reception path (12). As a result, a duplexer for an ICR cell of an FT-ICR mass spectrometry device is provided in which at least one electrode can be used for both ion excitation and for subsequent ion detection.

Abstract: A nuclear magnetic resonance (NMR) probe head for use in a room temperature bore of a superconducting NMR magnet cryostat for investigation of generally room temperature samples comprises a radio frequency (RF) receiving coil, a receiving coil preamplifier connected to the receiving coil, at least one additional coil and cryogenic means connected to the RF receiving coil, to the receiving coil preamplifier, and to the at least one additional coil for keeping the RF receiving coil, the preamplifier and the additional coil at a cryogenic temperature. The apparatus is improved in that at least one additional preamplifier is connected to the additional coil and to the cryogenic means the cryogenic means keeping the additional preamplifier at a cryogenic temperature. The apparatus exhibits improved performance and increased flexibility.

Abstract: A method for tuning of the probe head impedance (Z.sub.x) of an NMR receiver coil having a receiver circuit for an NMR signal with which, by means of an RF tuning signal (3), the probe head impedance (Z.sub.x) is tuned via a first reference signal produced with real reference resistance (R.sub.0) at one location M2 within the receiver circuit is characterized in that a reference impedance (Z.sub.0) is matched at an arbitrary location in the path of the RF tuning signal (3) in the receiver circuit (10; 11) in such a fashion that a second reference signal corresponding to the first reference signal at location M2 occurs at location M2 and that subsequently, the probe head impedance (Z.sub.x) is tuned to the second reference signal at location M2. In this fashion, in the path of the NMR signal at the input to the preamplifier, the number of necessary diodes, RF chokes and other components, which can lead to signal losses, is minimized.