Enabling liquid vapor analysis using synchrotron VUV single photon ionization mass spectrometry with a microfluidic interface

Abstract

Vacuum ultraviolet (VUV) single photon ionization mass spectrometry (SPI-MS) is a vacuum-based technique typically used for analysis of gas phase and solid samples, but not for liquids, due to the challenge in introducing volatile liquids in vacuum. Here we present the first demonstration of in situ liquid analysis by integrating the System for Analysis at the Liquid Vacuum Interface (SALVI) microfluidic reactor into VUV SPI-MS. Four representative volatile organic compound (VOC) solutions were used to illustrate feasibility of liquid analysis. Our results show accurate mass identification of the VOC molecules and reliable determination of appearance energy (AE) that is consistent with ionization energy (IE) for gaseous species in literature as reported. This work validates that the vacuum-compatible SALVI microfluidic interface can be utilized at the synchrotron beamline and enable in situ study of gas-phase molecules evaporating off the surface of a liquid, which holds importance in the study of condensed matter chemistry.

From atoms to aerosols: probing clusters and nanoparticles with synchrotron based mass spectrometry and X-ray spectroscopy

“…24 A recent innovation has been use of a microfluidic device at the ionization region of the mass spectrometer. 25 This device, which has a tiny orifice (2-3 microns), allows for sampling directly the gas phase molecules emanating from the liquid underneath, while maintaining vacuum in the mass spectrometer. We have applied this method to probe phase changes in ionic liquids 26 and dynamic electrochemistry in a Li2S8 battery.…”

“…136 Our nanoparticle source, coupled to VMI photoelectron spectroscopy could be implemented to follow excited state dynamics in nanoparticles, and charge transfer by embedding these nanoparticles in aqueous aerosols as demonstrated for CdSe nanocrystals 178 and quantum dots 179 using HHG sources. It should also be possible to couple graphene encapsulated cells, 180 microfluidic devices 25 and other reactors commonly used at the synchrotron into the interaction region of our VMI photoelectron spectrometer to enable the study of solvation and charge states in the excited state. The Advanced Light Source is over 25 years old now, as is the chemical dynamics beamline.…”

New Insights into Secondary Organic Aerosol Formation at the Air–Liquid Interface

“…[9][10] Nevertheless, recent studies show that integrating a vacuum compatible microreactor, namely system for analysis at the liquid − vacuum interface (SALVI) [11][12][13][14] and VUV SPI-MS, makes it possible to study aqueous reactions in a dynamic environment. [15][16] We present the combination of tunable synchrotron VUV SPI-MS and SALVI microreactor to observe molecular intermediates and products of glyoxal photooxidation at the a − l interface approximated by the liquid − vacuum interface in this work. [17][18] This in situ study of a − l interfacial SOA formation from photochemical oxidation using liquid VUV SPI-MS is the first to the best of our knowledge.…”

“…UV aged sample obtained at photon energy of 10.7 eV; and e) a photoionization efficiency plot of C3H6O5 + . The schematic diagram in (a) was adapted from Komorek et al, 2018 16.…”

Probing sulphur clusters in a microfluidic electrochemical cell with synchrotron-based photoionization mass spectrometry

“…Two 2 µm diameter holes 100 µm apart were pre-milled into a silicon nitride (SiN) membrane with the gold thin film WE already 65 sputter coated using a scanning electron microscope with the Focused Ion Beam (SEM-FIB). 11 The holes are necessary to allow the liquid to evaporate from the device under high vacuum (10 -7 Torr) in the main chamber to become subsequently ionized by The SALVI E-Cell devices were then sputter coated with a 30 nm gold (Au) thin film over the device so that it could be conductive as one of the electrodes in the ion optics module 5 of the single photon ionization mass spectrometer (SPI-MS), 12 as seen in Fig. 1.…”