Photoelectron spectroscopy and electronic structure of clusters of the group V elements. III. Tetramers: The2T2and2A1excited states of P+4, As+4, and Sb+4

摘要

Methods employing high resolution HeI (584 Aring;) photoelectron spectroscopy have been applied to the tetrameric clusters of the group V elements, to resolve details of vibronic and spinndash;orbit structure in the first three electronic states of P+4, As+4, and Sb+4. Measured spacings of distinct vibrational progressions in the ngr;1mode for the2A1states of P+4and As+4, yield vibrational frequencies of 577 (5) cmminus;1for P+4and 350 (6) cmminus;1for As+4. Franckndash;Condon factor calculations suggest bond length changes for the ions in the2A1states of 0.054 (3) Aring; for P+4and 0.060 (3) Aring; for As+4. Strong Jahnndash;Teller distortions in the ngr;2(e) vibrational mode dominate the structure of the2Eground states of the tetrameric ions. Both Jahnndash;Teller and spinndash;orbit effects appear in the spectra of the2T2states of the tetrameric ions, with the spinndash;orbit effect being dominant in Sb+4and the Jahnndash;Teller effect dominant in P+4. Vibrational structure is resolved in the P+4spectrum, and the ngr;3(t2) mode is found to be the one principally active in the Jahnndash;Teller coupling. A classical metalhyphen;droplet model is found to fit well with trends in the IPs of the clusters as a function of size.