The probability of passing molecules (SF6, CF3I) in a beam through a multichannel plate (MCP), which is cooled to T-s congruent to 80-85 K and inclined to the beam axes, is found to increase essentially when molecules are excited by a powerful infrared laser radiation into high vibrational states (with energy E-v >= 0.5-2.0 cV) as compared with unexcited (vibrationally cold) ones. The method is described and the first experimental results are presented. It is shown, that the probability of passing molecules through the MCP depends strongly on the frequency and energy density of exciting laser radiation. (c) 2006 Elsevier B.V. All rights reserved.