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CaF: All Spectra and All Dynamics R. W. Field, J. J. Kay, S. L. Coy, V. S. Petrovic, S. N. Altunata, B. M. Wong, and Ch. Jungen NSF
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Multichannel Quantum Defect Theory MQDT builds a complete description of something complicated, CaF, by combining complete (all states) descriptions of two isolated parts, CaF + and e -, at infinite separation. Space is divided into an infinite simple region and a compact region of complex interactions. The H eff matrix would be of infinite dimension. An e -, incident with definite ε, ℓ, scatters inelastically off of the ion-core in a definite v +,N + state. The building blocks are channels rather than individual electronic states. A channel consists of infinite number of states, with the e - in a particular mixed- ℓ form converging to a v +,N + state of the ion-core.
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MQDT The scattering of the e - off of the ion-core is described by the “Reaction Matrix,” K, which is expressed in terms of quantum defect matrix elements: K ij = tan(πμ ij ).. The μ ij are expanded as power series in internuclear distance, R, and energy. μ ij, dμ ij /dR, and dμ ij /dε are the fitted quantities. The MQDT equations yield eigenquantum defects and eigenvectors, which may be expressed in either the Hund’s case (b) or (d) basis sets. There are many useful, a priori known transformations between basis sets.
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Quantum defect matrix element values and derivatives obtained from fits to CaF Σ, Π, Δ, and Φ states. Uncertainties are indicated in parentheses. If no numerical value is given, the parameter has been held fixed at zero.
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Quality of fit for vibrationally-excited levels with low-n*
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Quality of fit in the vicinity of n* = 7.0. Vibronic states at this energy that belong to different vibrational quantum numbers are interleaved. Here, the classical period of electronic motion [proportional to (n*) 3 ] is approximately equal to the classical period of vibrational motion. Vibronic perturbations are frequent.
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Example of a strong vibronic (homogeneous) perturbation. In the absence of the perturbation, the 7.36 ‘p’ Π v=0 and 6.36 ‘p’ Π v=1 levels are nearly degenerate. The perturbation causes a ~45 cm -1 splitting of the levels and complete mixing of the two zero-order wavefunctions.
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Quality of fit in the n* = 16.5 – 17.5 region. Above n* 16, rotational interactions are ubiquitous and quite strong, causing the destruction of regular rotational patterns, which is evident here.
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Nonpenetrating States: Stacked Plot for N, N + Assignment
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Nonpenetrating States Live Near Integer n*
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High Resolution Detective Work Required
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Vibrational Autoionization: Single Channel (HLB-RWF)
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Case (b) to Case (d) Transformation case (b)case (d) even N f Σ,Π,Δ,ΦN + =N-3,N-1,N+1,N+3 + paritydΣ,Π,ΔN + =N-2,N, N+2 [10] p Σ,Π N + =N-1,N+1 s Σ N + =N -parityf -,Π,Δ,ΦN + =N-2,N,N+2 [6] d -,Π,Δ N + =N-1,N+1 p -,Π N + =N s - N + =-
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Multichannel Autoionization Want total autoionization rate from every n*,N,v + =1 level and fractional yields into different N + levels of CaF + v + =0. Transform the μ and dμ/dR matrices from case (b) to case (d). Solve the MQDT equations to get eigenvectors expressed in case (d). For the optically selected eigenstate, compute expectation value of [dμ/dR(d)] T dμ/dR(d). This can be broken down into individual N + contributions
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