Enhancement of Rb fine-structure transfer in 4He due to three-body collisions.
Using ultrafast laser excitation and time-correlated single-photon counting techniques, we have measured the collisional mixing rates between the rubidium 5(2)P fine-structure levels in the presence of (4)He gas. A nonlinear dependence of the mixing rate with (4)He density is observed. We find Rb fine-structure transfer is primarily due to binary collisions at (4)He densities of < or = 10(19) cm(-3), while at greater densities, three-body collisions become significant. We determine a three-body collisional transfer rate coefficient (5(2)P(3/2) --> 5(2)P(1/2)) of 1.25(9)x10(-32) cm(6)/s at 22 degrees C.
Sell
J F
JF
Laser and Optics Research Center, U.S. Air Force Academy Department of Physics, USAF Academy, Colorado 80840, USA. jerry.sell@usafa.edu
Gearba
M A
MA
Patterson
B M
BM
Genda
T
T
Naumann
B
B
Knize
R J
RJ