Jump to main content
Jump to site search
Access to RSC content Close the message box

Continue to access RSC content when you are not at your institution. Follow our step-by-step guide.

Issue 3, 2013
Previous Article Next Article

Visualization of mass transport and heat transfer in the FAPA ambient ionization source

Author affiliations


Ambient desorption/ionization mass-spectrometry (ADI-MS) has shown tremendous potential for the direct analysis of materials in the open atmosphere. Unfortunately, processes governing analyte desorption and transport into the mass spectrometer, which ultimately limit sampling reproducibility and quantification, have not been investigated for most ADI-MS sources. For plasma-based ADI-MS sources, such studies are further complicated because the discharge support gas is optically transparent. Here, two methods were employed to probe these otherwise invisible phenomena. Specifically, schlieren imaging and infrared (IR) thermography were utilized to visualize plasma-gas flow and heat transfer, respectively, from a pin-to-capillary geometry flowing atmospheric-pressure afterglow (FAPA) ambient ionization source. The influence of operating conditions was investigated, including plasma-gas flow rate and source capillary diameter. Interactions of the desorption/ionization beam with a sample probe or a sample surface before it is captured by a mock mass spectrometer interface were also explored. These experiments showed that schlieren imaging is a viable means for visualization of the plasma transport gas, and that coupling with IR thermography yields information on gas and temperature distributions. Schlieren images revealed that the existence of a discharge can alter by up to 8 cm the location where the flowing afterglow transitions from laminar to turbulent flow. Addition of a sample-introduction probe into the plasma gas perturbed the width of the gas beam by 1.5 cm. Additionally, helium impinging on a surface expanded rapidly, unless an interface was present to capture the gas, while local heating was confined to a small area (<1 cm2), based on 75% of the maximum temperature, compared to background.

Graphical abstract: Visualization of mass transport and heat transfer in the FAPA ambient ionization source

Back to tab navigation

Supplementary files

Article information

30 Nov 2012
22 Jan 2013
First published
22 Jan 2013

J. Anal. At. Spectrom., 2013,28, 379-387
Article type

Visualization of mass transport and heat transfer in the FAPA ambient ionization source

K. P. Pfeuffer, J. T. Shelley, S. J. Ray and G. M. Hieftje, J. Anal. At. Spectrom., 2013, 28, 379
DOI: 10.1039/C3JA30353E

Social activity

Search articles by author