Measurement of the spin-exchange cross section in the collision of H atoms with O2 and NO by means of stored atomic-beam spectroscopy

The spin-exchange cross section ? for the collision of hydrogen atoms with O2 and NO have been measured by means of stored atomic-beam spectroscopy. Average values at room temperature are ?(H-O2)=(10±1)×10-16 cm2 and ?(H-NO)=(13±1)×10-16 cm2. A comparison between our data and pulsed-maser measurements is presented. The development of a passive hydrogen maser based on our bolometric detection technique is proposed.