The 67 th International Symposium on Molecular Spectroscopy, June 2012 Ruohan Zhang, Chengbing Qin a and Timothy C. Steimle Dept. Chem. & BioChem., Arizona State University, Tempe, AZ,USA Funded by: DoE-BES The Optical Stark Spectrum of the [17.8]0 + -X 1  + Band of AuF Thomas Varberg Mccalaster College, St Paul, MN, USA a Visitor from Dept. Chem. Phys. University of Science and Technology of China, Hefei, Anhui , China & Zeeman

“ Noble” metals actually have a rich and an valuable chemistry Noble metals Review by Pyykkö High speed of electrons near the nucleus  mass increase  stabilization and contraction The contraction of the 6s orbital  unique chemical properties of Au. Spectroscopic methods for probing electronic wavefunction: a) Stark effect b) Zeeman effect c) Hyperfine interactions 197 Au(I=3/2)

Previous Experimental Studies: Evans & Gerry JACS FTMW  B v, eQq(Au), C I (Au) & C I (F) Knurr, Butler & Varberg JPC-A 2009 [17.7]1-X 1  +  [17.7] mag. Hyp. Okabayashi et al CPL mm-wave  B v, eQq(Au), C I (Au) & C I (F) Theoretical Studies (Very Numerous); Recent Ones : Andreev & BelBruno CPL Visible Emission   =0&1  X 1  + Butler….& Varberg JPC-A 2010 cw-dye laser [17.7]1,[14.0]1 & [17.8]0-X 1  + sub-Doppler LIF; sputtering source Hill & Peterson JCTC 2012 Coupled Cluster prediction  e, r e, ect. Goll et al Phys. Rev. A 2007 DFT/Wavefunc hybrid  el Ref #1 Schwerdtfeger et al JCP 2011 Pseudopoteintials  el Ref #2 Fernández & Balbás PCCP 2011 vdW-DF  e, r e, ect.  el Ref #3

Well collimated molecular beam Rot.Temp.<10 K Single freq. tunable laser radiation PMT Gated photon counter Experimental set up for LIF studies Helmholtz coils Optical Zeeman Spectroscopy Stark plates Optical Stark spectroscopy Metal target Pulse valve skimmer Ablation laser SF 6 & Carrier Au tube

Observations-Field-Free LIF Varberg’s JCP 2010 Pulsed dye laser; sputtering source; T  600K FWHM  3 GHz P(1) R(0) Sub-Doppler I 2 Beam LIF AuF Current study cw dye laser; sputtering source; T  10K FWHM  40 MHz

P(1) - Stark Effect 0 V/cm 3010V/cm 0 V/cm X1X1 J=1 M J =0 MJ=1MJ=1 [17.8]0  J=0 MJ=0MJ=0 Electric Field Energy C C B B Field Free A A A A Laser Wavenumber LIF Signal

Analysis of FF & Stark Spectrum of [17.8]0+-X 1  +  (case(a))  S  J  > Basis function: H Rot =BJ 2 H Stark =E∙  el Field-Free Spectrum JCP 2010  T = cm -1 ; B”= cm -1 ; B’= cm -1 Stark Spectrum  8  8 representation ( J=0-7)  (X 1  + ) = (23) D  ([17.8]  + ) = (60) D

Discussion-Stark Dipole moment  (X 1  + ) = (23) D 9D Note: Au +1 F -1 Goll et al 2007 ;DFT/wavefunc hybrid Note: No predictions for [17.8]0 + state DFT 3.60 CSSD(T) 4.46 CSSD(T)/DFT 4.42 Method Value (D) CAM-DFT 4.24 “CAM” =Coulomb Attenuated The “CAM-DFT” method does indeed give the best results for m predictions, as proposed in Ref. 1.

Discussion-Stark Elec. Dipole moment  (X 1  + ) = (23) D Ref. 2 Schwerdtfeger et al JCP 2011 Pseudopoteintials “SC-SRPP-S” =Small Core; Scalar Relativistic; Pseudo- Potential -Stuttgart “SC-NRPP-S” =Small Core; Non-Relativistic; Pseudo- Potential -Stuttgart Relativity matters: vs compared to experimental value of D

Discussion-Stark Dipole moment  (X 1  + ) = (23) D Functional Value (D) DRSLL 4.06 LMKLL 3.94 KBM 3.94 Non-local correlation van der Waals PBE 3.96 Generalized Gradient Approximation Ref. 3 ;Fernández & Balbás PCCP 2011 vdW-DF  e, r e, ect. General Comment: All high-level predictions of  (X 1  + ) are good. Why? 1) Simple description of X 1  + : Au + (5d 10 )F - (3p 6 ) single Slater determinant 2)  not  strongly  dependent on relativistic effects (only valence electrons)

Zeeman effect Motivation: Insight into [17.8]0 + state. If [17.8]0 + = 1  +  non-magnetic If [17.8]0 + = 3    Hund’s case (a) limit)  non-magnetic  =0 & Eq. 1  non-magnetic Eq. 1 Observations: 4500 G. “Perp.” Field-free P(1) Field-free R(0) 4500 G. “Perp.” non-magnetic magnetic

Analysis Zeeman Spectrum of [17.8]0+-X 1  + All observed shifts due to the [17.8]0 + state. Phenomenological model for shifts [17.8]0 + state:  E zee =  B  g J  B Z  M J Results: Non-zero g J due to rotational mixing with [17.7]1 state ? Detailed interpretation in progress. [17.8]0 + J gJgJ  E ( MHz )

Thank you! Future plans: additional Au molecules (AuC, Au 2 …) Permanent electric dipole moments of [17.8]0 + & X 1  + have been determined  Test methodologies for relativistic electronic structure predictions Magnetic g-factors for [17.8]0 + & X 1  + have been determined  [17.8]0 + mixing Summary