Abstract: The laser ablation-molecular beam(LA-MB) method is useful for studying the reactions of metal ions with molecular clusters. Reactions of magnesium plasma with methanol clusters were studied by using this method. A specially designed reaction cell was used as a fast flow reactor operated under thermal conditions, and the reaction products were measured with a time-of-flight(TOF) mass spectrometer. Surprisingly, several series of cluster ions with complex sizes and intensity distributions were obtained when the laser ablating was applied to different parts of the molecular beam. In the front part of the molecular beam, strong Mg⁺(CH₃OH)_n(n=0—5) and weak H⁺(CH₃OH)_n(n=0—5) cluster ions were observed with relatively small cluster sizes; in the middle part of the molecular beam, the main cluster ions were H⁺(CH₃OH)_n(n=6—17) and H⁺(H₂O)₂(CH₃OH)_n(n=6—17) with a relatively large cluster size and a weak intensity; in the back part of the molecular beam, two new series of cluster ions, MgO⁺(H₂O)(CH₃OH)_n(n=6—10) and MgOCH⁺₃(CH₃OH)_n(n=6—10), were obtained and accompanied by weak H⁺CH₃OH)_n(n=4—7) and H⁺(H₂O)₂(CH₃OH)_n(n=3—6). The formation mechanisms and speed characteristics of the cluster ions are discussed in this article.

Key words: Laser ablation-molecular beam, Mg plasma, Methanol cluster, Ion-molecular cluster reaction, Formation mechanism, Laser ablation-molecular beam, Mg plasma, Methanol cluster, Ion-molecular cluster reaction, Formation mechanism