Related Experiment Video
Updated: Jun 11, 2026

Experimental Methods for Efficient Solar Hydrogen Production in Microgravity Environment
Published on: December 3, 2019
Experimental results for H2 formation from H- and H and implications for first star formation
1Columbia Astrophysics Laboratory, Columbia University, New York, NY 10027, USA. hkreckel@illinois.edu
Abstract:
During the epoch of first star formation, molecular hydrogen (H2) generated via associative detachment (AD) of H- and H is believed to have been the main coolant of primordial gas for temperatures below 10(4) kelvin. The uncertainty in the cross section for this reaction has limited our understanding of protogalaxy formation during this epoch and of the characteristic masses and cooling times for the first stars. We report precise energy-resolved measurements of the AD reaction, made with the use of a specially constructed merged-beams apparatus. Our results agreed well with the most recent theoretically calculated cross section, which we then used in cosmological simulations to demonstrate how the reduced AD uncertainty improves constraints of the predicted masses for Population III stars.
Related Concept Videos
Formation of Halohydrin from Alkenes
Standard Enthalpy of Formation
Molecular Orbital Theory II
Hess's Law
Reduction of Alkenes: Catalytic Hydrogenation
Metals like palladium, platinum, and nickel are commonly used in their solid forms — fine powder on an inert surface. As these catalysts remain insoluble in the reaction mixture, they are referred to as heterogeneous catalysts.
The hydrogenation process takes place on the surface of...
Electrophilic 1,2- and 1,4-Addition of HX to 1,3-Butadiene