The 67 th International Symposium on Molecular Spectroscopy, June 2012 Ruohan Zhang, Chengbing Qin a and Timothy C. Steimle Dept. Chem. & BioChem., Arizona.

The 67th International Symposium

on Molecular Spectroscopy, June 2012

Ruohan Zhang, Chengbing Qina 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+-X1+ 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 230026, 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 197Au(I=3/2)

Previous Experimental Studies:

• Evans & Gerry JACS -2000 FTMW Bv, eQq(Au), CI (Au) & CI (F)

• Knurr, Butler & Varberg JPC-A 2009 [17.7]1-X1+ [17.7] mag. Hyp.

• Okabayashi et al CPL -2002 mm-wave Bv, eQq(Au), CI (Au) & CI (F)

Theoretical Studies (Very Numerous); Recent Ones :

• Andreev & BelBruno CPL -2000 Visible Emission =0&1X1+

• Butler….& Varberg JPC-A 2010 cw-dye laser [17.7]1,[14.0]1 & [17.8]0-X1+ sub-Doppler LIF; sputtering source

• Hill & Peterson JCTC 2012 Coupled Cluster prediction e, re, 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-DFe, re, ect. el Ref #3

Well collimatedmolecular beamRot.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

SF6

& Carrier

Au tube

Observations-Field-Free LIF

Varberg’s JCP 2010Pulsed dye laser; sputtering source; T 600KFWHM 3 GHz

P(1)

R(0)

Sub-Doppler I2

Sub-Doppler I2

Beam LIF AuF

Beam LIF AuF

Current studycw dye laser; sputtering source; T 10KFWHM 40 MHz

P(1) - Stark Effect

0 V/cm 3010V/cm

3010 V/cm 0 V/cm

X1

J=1

MJ=0

MJ=1

[17.8]0

J=0

MJ=0

Electric Field

Energ

yC

CB

B

Field Free

A

A

A

A

Laser Wavenumber17755.1217755.10

LIF

Sig

nal

Analysis of FF & Stark Spectrum of [17.8]0+-X1+

(case(a))SJ>Basis function:

HRot=BJ2 HStark=E∙ el

Field-Free SpectrumJCP 2010

T =17776.441cm-1; B”= 0.263409 cm-1 ; B’= 0.2532162cm-1

Stark Spectrum 88 representation ( J=0-7)

(X1+) = 4.148 (23) D

([17.8]+) = 2.201 (60) D

Discussion-StarkDipole moment (X1+) = 4.148 (23)

D9DNote: Au+1F-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-StarkElec. Dipole moment (X1+) = 4.148 (23)

DRef. 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: 5.229 vs. 4.046 compared to experimental value of 4.148 D

Discussion-StarkDipole moment (X1+) = 4.148 (23)

D

Functional Value (D)

DRSLL 4.06

LMKLL 3.94

KBM 3.94

Non-local correlation van der Waals

PBE 3.96Generalized

Gradient Approximation

Ref. 3 ;Fernández & Balbás PCCP 2011 vdW-DFe, re, ect.

General Comment: All high-level predictions of (X1+) are good. Why?

1) Simple description of X1+: Au+(5d10)F-(3p6) single Slater determinant2) notstronglydependent on relativistic effects (only valence electrons)

Zeeman effectMotivation: Insight into [17.8]0+ state.

If [17.8]0+ = 1+ non-magnetic

If [17.8]0+ = 3Hund’s case (a) limit) non-magnetic

=0 & Eq. 1 non-magnetic

Eq. 1

Observations:

4500 G. “Perp.”

Field-freeP(1)Field-freeR(0)

4500 G. “Perp.”

non-magnetic magnetic

Analysis Zeeman Spectrum of [17.8]0+-X1+

All observed shifts due to the [17.8]0+ state.

Phenomenological model for shifts [17.8]0+ state: Ezee = B gJ BZ MJ

Results:

1 110 0.016

2 100 0.015

3 105 0.015

0 0 0.000

Non-zero gJ due to rotational mixing with

[17.7]1 state ?Detailed interpretation in

progress.

[17.8]0+ J gJE (MHz)

Thank you!

Future plans: additional Au molecules (AuC, Au2…)

Permanent electric dipole moments of [17.8]0+ & X1+ have been determined

Test methodologies for relativistic electronic structure predictions

Magnetic g-factors for [17.8]0+ & X1+ have been determined

[17.8]0+ mixing

Summary