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10:44
Preparation of Carbon Nanosheets at Room Temperature
Published on: March 8, 2016
Hydronium ion motion in nanometer 3-methyl-pentane films
Richard C Bell1, Kai Wu, Martin J Iedema
1Chemistry Department, The Pennsylvania State University, Altoona College, Altoona, Pennsylvania 16601, USA. rcb155@psu.edu
The Journal of Chemical Physics
|July 21, 2007
Summary
This study reveals hydronium (D(3)O(+)) and cesium (Cs(+)) ions exhibit similar mobilities in glassy 3-methyl-pentane (3MP) films. Ion transport behavior was accurately modeled, with deviations at higher electric fields and slower temperature dependence than predicted.
Area of Science:
- Physical Chemistry
- Materials Science
- Surface Science
Background:
- Understanding ion transport in amorphous solid films is crucial for various applications.
- Glassy hydrocarbon films like 3-methyl-pentane (3MP) present unique environments for ion dynamics.
Purpose of the Study:
- To investigate the mobility and transport mechanisms of hydronium (D(3)O(+)) and cesium (Cs(+)) ions in glassy 3MP films.
- To evaluate the applicability of continuum-based ion mobility models to these systems.
- To explore the influence of film thickness, electric field, and temperature on ion motion.
Main Methods:
- Ion soft-landing technique to deposit ions onto vapor-deposited 3MP films on a Pt(111) substrate.
- Variable temperature (84-104 K) and electric field strength measurements.
- Analysis of ion drift velocity and mobility as a function of film thickness (25-20,000 ML).
Main Results:
- Hydronium (D(3)O(+)) and cesium (Cs(+)) ions displayed remarkably similar mobilities within the 3MP films.
- Ion mobilities ranged from approximately 10(-18) to 10(-13) m(2) V(-1) s(-1).
- A continuum-based ion mobility model provided a good prediction of ion motion, even with interfacial perturbations.
- Drift velocity showed linear dependence on the electric field below ~2 x 10(8) V/m, deviating at higher fields.
- Observed temperature dependence of mobility was weaker than predicted by Stokes' law.
Conclusions:
- The motion of D(3)O(+) and Cs(+) in 3MP films can be largely described by continuum models.
- Deviations from linearity at high electric fields and slower-than-expected temperature dependence suggest the influence of film microstructure near the glass transition temperature (77 K).
- The findings contribute to understanding ion transport phenomena in glassy organic solids.
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