We have applied the laser-ablation technique for the study of depolarization effects of the [Formula Presented] [Formula Presented] and [Formula Presented] states of Ba with He gas in the wide temperature range of 10–300 K. The depolarization cross sections of both states have been found to have a positive temperature dependence, indicating that the responsible interaction is not a van der Waals type. A tentative and qualitative explanation for the difference of the temperature dependence between [Formula Presented] [Formula Presented] and [Formula Presented] is given in terms of electron density distribution. © 1998 The American Physical Society.