@article { ISI:000262355000018, title = {Mechanism of Collisional Spin Relaxation in (3)Sigma Molecules}, journal = {PHYSICAL REVIEW LETTERS}, volume = {102}, number = {1}, year = {2009}, month = {JAN 9}, pages = {013003}, abstract = {We measure and theoretically determine the effect of molecular rotational splitting on Zeeman relaxation rates in collisions of cold (3)Sigma molecules with helium atoms in a magnetic field. All four stable isotopomers of the imidogen (NH) molecule are magnetically trapped and studied in collisions with He-3 and He-4. The He-4 data support the predicted 1/B-e(2) dependence of the collision-induced Zeeman relaxation rate coefficient on the molecular rotational constant B-e. The measured He-3 rate coefficients are much larger than the He-4 coefficients, depend less strongly on B-e, and theoretical analysis indicates they are strongly affected by a shape resonance. The results demonstrate the influence of molecular structure on collisional energy transfer at low temperatures.}, issn = {0031-9007}, doi = {10.1103/PhysRevLett.102.013003}, author = {Campbell, Wesley C. and Tscherbul, Timur V. and Lu, Hsin-I and Tsikata, Edem and Krems, Roman V. and Doyle, John M.} }