Highly sensitive single-molecule detection in slow protein ion beams

TL;DR

This paper demonstrates that superconducting nanowire detectors significantly improve single-molecule detection sensitivity in low-energy ion beams, enabling advanced mass spectrometry and molecular discrimination.

Contribution

It introduces the use of superconducting nanowire detectors in quadrupole mass spectrometry, achieving unprecedented sensitivity at low impact energies.

Findings

Sensitivity surpasses conventional detectors by three orders of magnitude.

Detectors can discriminate molecules by impact energy and charge.

Array configurations enable low-energy ion beam profilometry.

Abstract

The analysis of proteins in the gas phase benefits from detectors that exhibit high efficiency and precise spatial resolution. Although modern secondary electron multipliers already address numerous analytical requirements, new methods are desired for macromolecules at low energy. Previous studies have proven the sensitivity of superconducting detectors to high-energy particles in time-of-flight mass spectrometry. Here we explore a new energy regime and demonstrate that superconducting nanowire detectors are exceptionally well suited for quadrupole mass spectrometry. Our detectors exhibit an outstanding quantum yield at remarkably low impact energies. Notably, at low ion energy, their sensitivity surpasses conventional ion detectors by three orders of magnitude, and they offer the possibility to discriminate molecules by their impact energy and charge. By combining these detectors into arrays, we demonstrate low-energy ion beam profilometry, while our cryogenic electronics pave the way for future developments of highly integrated detectors.