Absolute Integrated Band Strength and Magnetic Dipole Transition Moments in the ²P_3/2 → ²P_1/2 Fine Structure (with Hyperfine Structure) Transition of the Iodine Atom: Experiment and Theory

Abstract

Previous experimental and theoretical results on the strength of the important fine structure transition in the Iodine atom scatter over a very wide range, indicating great uncertainty. We have therefore carried out new theoretical calculations and experiments to reinvestigate the transition probability between the fine structure levels 2P3/2 and 2P1/2 in the electronic ground configuration of atomic iodine. In the experiments a tunable, narrow band width, near‐IR laser was used to measure the iodine absorption spectrum with sub‐Doppler resolution. The I‐atoms in the 2P3/2 ground state are produced either in a I2 = 2I equilibriums at elevated temperatures or from IR‐multiphoton dissociation of CF3I, CF3CHFI or C6F5I. The two different experimental methods to produce I‐atoms in the ground state allow for a careful check on possible systematic errors. In the experiments an integrated absorption cross section of Gexp = ∫ σ(v) dln v = (1050±250) fm2 was determined, corresponding to a radiative lifetime of 140 ms for spontaneous emission from the upper level. We have in addition carried out nonrelativistic MCHF calculations and relativistic Dirac‐Fock calculations on this transition. The results of the MCHF calculations (1200 fm2) agree well with experiment and a crude estimate from a simple LS coupling model.

Zero electron kinetic energy and photoelectron spectroscopy of the XeI− anion

“…The deviation at short range corresponds to a slightly smaller ⌬ so than for atomic iodine. 44 Such a reduction is not unexpected and was also observed for iodine in Xe matrices. 59 Finally we note that if one uses two of the neutral potentials to determine the third, i.e., allowing no variation in ⌬ so (R), then the repulsive wall of the generated potential deviates significantly from the ''best fit'' potential.…”

“…1, we expect to observe two band systems, which are separated by approximately the spin-orbit constant of atomic iodine (0.942 65 eVϭ7603.0 cm Ϫ1 ). 44 The lower energy band system is shown in Fig. 2, and results from transitions to the X1/2 and I3/2 states.…”

Zero electron kinetic energy and threshold photodetachment spectroscopy of XenI− clusters (n=2–14): Binding, many-body effects, and structures

“…1 and our earlier studies of other diatomic and polyatomic rare gas halide species, we expect to observe two sets of features separated by approximately the spin-orbit splitting ⌬ so ͑I͒ of atomic iodine (7603.0 cm Ϫ1 ϭ0.942 65 eV). 46 The lower-energy features ͑Figs. 2-4͒ are due to transitions from the anion cluster to electronic states correlating with the 2 P 3/2 ground state of the iodine atom, and those at higher energy arise from transitions from the anion cluster to states referring asymptotically to the iodine 2 P 1/2 state ͑Fig.…”

Direct Kinetic Measurements of Reactions between the Simplest Criegee Intermediate CH2OO and Alkenes

“…The uncertainty of is estimated as 10% because it is also sensitive to systematic uncertainties in [O 2 ]. That leaves the following contributors to the uncertainty: , which has a relative uncertainty of 20% as reported by Ha et al 2 , and and 375 , which have 16 and 27% relative uncertainty, respectively, as shown in Table S1. Combining these uncertainties using the above equation…”