Probing Liquid Surfaces under Vacuum Using SEM and TOF-SIMS
Applying vacuum-based molecular probes of liquid surfaces would aid many environmental, biological, and industrial studies. However the high vapor pressure of water and most organic solvents largely prohibit this use. We report a newly developed versatile and self-contained vacuum interface for high-vapor pressure liquid surfaces, and its application in a time of flight secondary ion mass spectrometer (TOFSIMS) and scanning electron microscope (SEM). The self-contained module requires no wires or tubing connections to the outside of the instrument. It uses a microfluidic channel with a 3 micrometer diameter window into the flowing fluid beneath it. This window supports the liquid against the vacuum by the liquid’s surface tension, while limiting the high-density vapor region traversed by the probe beams to only a few microns. This aperture size also limits temperature and concentration changes due to evaporation of the solvent. The beam damage caused by the probe beams is largely negligible, as the flowing liquid surface self-renews. We demonstrate the performance of this microfluidic interface for in situ liquid surface TOFSIMS (ISLS-TOFSIMS) and SEM (ISLS-SEM) for chemical analysis of liquid surfaces. This device enables in situ liquid (ISL) studies in a wide range of vacuum analytical methods beyond SEM and TOFSIMS.
- Research Organization:
- Pacific Northwest National Lab. (PNNL), Richland, WA (United States). Environmental Molecular Sciences Lab. (EMSL)
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- AC05-76RL01830
- OSTI ID:
- 1019201
- Report Number(s):
- PNNL-SA-76770; 36601; 42330; 36603; KC0301020; TRN: US201114%%686
- Journal Information:
- Lab on a Chip, 11(15):2481-2484, Vol. 11, Issue 15
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
APERTURES
CHEMICAL ANALYSIS
ELECTRON MICROSCOPES
EVAPORATION
MASS SPECTROMETERS
ORGANIC SOLVENTS
PERFORMANCE
PROBES
SURFACE TENSION
VAPOR PRESSURE
WATER
WINDOWS
in situ
liquid interface
surface
TOFSIMS
SEM
microfluidic
vacuum
Environmental Molecular Sciences Laboratory