PRODUCTION OF YBH-REACTION OF YB+ IN EXCITED-STATES WITH H-2 GAS( BY CHEMICAL)

It is known that fluorescence of trapped Yb+ ions fades with continuou s driving of the S-2(1/2)-P-2(1/2) transition in the presence of buffe r gases. This phenomenon has been interpreted as being caused by popul ation trapping in the F-2(7/2) state of Yb+. As another cause of the f luorescence disappearance, we found the production of YbH+ by chemical reaction of Yb+ in excited states with H-2 gas. We found that the wav elengths of 369.482, 369.202, and 368.947 nm, formerly assigned as wav elengths for deexcitation of Yb+ in the F-2(7/2) state to the S-2(1/2) ground state, are actually photodissociation lines of YbH+. The chang e of the resonance point of rf resonance absorption signals indicates the production and dissociation of YbH+ ions. The production of YbH+ m ay be a problem in establishing frequency standards using buffer-gas-c ooled Yb+, owing to difficulty in removing H-2 gas from vacuum systems .