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Updated: Aug 2, 2026
08:55
Methods of Ex Situ and In Situ Investigations of Structural Transformations: The Case of Crystallization of Metallic Glasses
Published on: June 7, 2018
Cold molecule spectroscopy for constraining the evolution of the fine structure constant
Eric R Hudson1, H J Lewandowski, Brian C Sawyer
1JILA, National Institute of Standards and Technology and University of Colorado, Boulder, CO 80309-0440, USA. ehudson@jilau1.colorado.edu
Physical Review Letters
|May 23, 2006
Summary
Precise microwave transition measurements of the hydroxyl radical (OH) were achieved using a Stark decelerator. These findings enhance measurement precision significantly, enabling new tests of fundamental physics with interstellar molecules.
Area of Science:
- Atomic and Molecular Physics
- Astrophysics
- Fundamental Physics
Background:
- The hydroxyl radical (OH) is a key molecule in astrochemistry and a sensitive probe of physical conditions in space.
- Precise laboratory measurements of OH transitions are crucial for interpreting astronomical observations and testing fundamental physical constants.
Purpose of the Study:
- To perform highly precise measurements of ground-state, Lambda-doublet microwave transitions in the hydroxyl radical (OH).
- To improve the precision of previous measurements by leveraging advanced molecular beam techniques.
Main Methods:
- Utilizing slow, cold hydroxyl radical molecules produced by a Stark decelerator.
- Measuring Lambda-doublet microwave transitions in the ground state of OH.
Main Results:
- Achieved a 25-fold improvement in precision for the F'=2-->F=2 transition, yielding (1 667 358 996 +/- 4)Hz.
- Attained a tenfold improvement in precision for the F'=1-->F=1 transition, yielding (1 665 401 803 +/-12)Hz.
Conclusions:
- The enhanced precision of these laboratory frequencies allows for sensitive tests of the variation of fundamental constants.
- Comparison with OH megamaser observations can provide a sensitivity of 1 part per million (ppm) for Delta(alpha/alpha) over cosmological timescales.
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