Cryogenic micro-calorimeters for mass spectrometric identification of neutral molecules and molecular fragments

Abstract

We have systematically investigated the energy resolution of a magnetic micro-calorimeter (MMC) for atomic and molecular projectiles at impact energies ranging from E ≈ 13 to 150 keV. For atoms we obtained absolute energy resolutions down to ∆E ≈ 120 eV and relative energy resolutions down to ∆E/E ≈ 10 −3 . We also studied in detail the MMC energy-response function to molecular projectiles of up to mass 56 u. We have demonstrated the capability of identifying neutral fragmentation products of these molecules by calorimetric mass spectrometry. We have modeled the MMC energy-response function for molecular projectiles and conclude that backscattering is the dominant source of the energy spread at the impact energies investigated. We have successfully demonstrated the use of a detector absorber coating to suppress such spreads. We briefly outline the use of MMC detectors in experiments on gas-phase collision reactions with neutral products. Our findings are of general interest for mass spectrometric techniques, particularly for those desiring to make neutral-particle mass measurements.

Single‐molecule mass spectrometry

“…These detectors can also be used to detect neutral molecules in tandem MS experiments. Novotný et al () used a microcalorimeter to study the fragmentation pathways of CH 3 + and acetone ions. In these experiments, the precursor ions had a known kinetic energy from their acceleration potential, and the kinetic energies of fragments (including neutral fragments) were proportional to their masses.…”

“…In 2006, Ohkubo et al () detected neutral and ionic PSD fragments of 200 kDa polystyrene and BSA ionized with MALDI. Ohkubo et al () have also performed tandem MS measurements on acetyl and acetone ions with an STJ, albeit with worse energy resolution than Novotný et al () managed a few years later. The ability to detect neutral fragments gave them deeper insight into fragmentation pathways than is attainable from conventional MS experiments.…”

Demonstration of a scalable frequency-domain readout of metallic magnetic calorimeters by means of a microwave SQUID multiplexer

“…Though Metallic magnetic calorimeters (MMCs) are low-temperature particle detectors that use a paramagnetic temperature sensor sitting in a weak magnetic field to convert an energy input into a magnetic flux change which can be precisely measured using a superconducting quantum interference device (SQUID). 1,2 MMCs have proven to be highly suitable detectors for various applications including high-resolution X-ray spectroscopy in atomic and nuclear physics, 3,4 nuclear forensics, 5,6 radiation metrology, 7-12 direct neutrino mass determination, 13 searches for neutrinoless double beta decay 14,15 and mass spectrometry 16 since they provide an excellent energy resolution, a very fast intrinsic signal rise time, a high quantum efficiency, a large energy bandwidth as well as a highly linear detector response. State-of-the-art MMC soft X-ray detectors, for example, reach an energy resolution ∆E FWHM = 1.58 eV for 5.9 keV photons and a signal rise time τ rise < 100 ns.…”

MOCCA: A 4k-Pixel Molecule Camera for the Position- and Energy-Resolving Detection of Neutral Molecule Fragments at CSR

“…2. The concept of this detector and preparing investigation of its underlying physical principles have been discussed in detail by Novotný, Gamer et al [3,4]. MOCCA is a micro-calorimeter particle detector.…”