Study on the interaction between different solute molecules in a molecular beam produced by the spray-jet technique: an application to dendrimer/dye system Toshiki Yamada a,*, Maofa Ge a, Hidenori Shinohara a, Katsumi Kimura b, Shinro Mashiko a a Kansai Advanced Research Center, Communications Research Laboratory, 588-2 Iwaoka, Kobe 651-2401, Japan b super-Molecular Photonics Joint Research Laboratory, National lnstitute for Materials Science, 2268-1 Anagahora, Nagoya 463-0003. Japan Received 15 July 2003; in final form 19 August 2003 Abstract We report on an investigation into the interaction between different neutral non-volatile solute molecules in a molecular beam produced by the spray-jet technique that enables us to produce a molecular beam from a sprayed mist of a sample solution. This technique is applied to poly(propylene imine) dendrimer and 4-dicyanomethylene-2-methyl6-p-dimethylaminostyryl-4H-pyran (DCM) systems. Resonantly enhanced multiphoton ionization of DCM in the DCM/dendrimer molecular beam leads to an efficient reaction between the dendrimer and DCM. The REMPI excitation spectra provide insights into the interaction between DCM and dendrimer molecules in the gas phase for the first time in these experiments.