The even-parity autoionizing resonance series 3p^5np′[3/2]1,2, 3p^5np′[1/2] 1, and 3p^5nf′[5/2]3 of Ar have been investigated exciting from the two metastable states 3p^54s[3/2]2 and 3p^54s′[1/2]0 in the photon energy range of 32500-35600 cm^-1 with an experimental band- width of ～0.1 cm^-1. The excitation spectra of the even-parity autoionizing resonance series show typical asymmetric line shapes. New level energies, quantum defects, line profile index and resonance widths, resonance lifetime and reduced widths of the autoionizing resonances are derived by a Fano-type line-shape analysis. The line profile index q and the resonance widths F are shown to be approximately proportional to the effective principal quantum number n^＊. The line separation of the 3p^5np′ autoionizing resonances is discussed.
We present a first velocity map imaging study on the 234 nm photodissociation dynamics of two carbon-chain branched alkyl bromides, neopentyl bromide （denoted as NPB） and tert- pentyl bromide （denoted as TPB）. Unlike the 234 nm photodissociation of the unbranched n-C5H11Br molecule where only a direct fission of the C-Br bond is involved, the branched NPB and TPB molecules exhibit one and two more independent dissociation pathways with much energy being decayed via an extensive excitation of the bending modes of the parent molecules prior to the C-Br bond fission. This observation strongly suggests that the dissociation coordinate for the two carbon-chain branched molecules is no longer solely ascribed to the C-Br stretching mode but rather a combination of the bending-stretching modes.
