Application of 2D fluorescence spectroscopy to Metal Containing Species Damian L. Kokkin and Timothy Steimle. Department of Chemistry and Biochemistry

Why are metal molecules important? Catalysis High temperature chemistry Materials science Astrophysics Outline: 1.Development of 2D spectroscopy for metal containing molecules. 2.Optical Stark Spectroscopy of NiO

2D fluorescence spectroscopy Applied successfully in the past to study complex chemical environments – Two-dimensional fluorescence (excitation/emission) spectroscopy as a probe of complex chemical environmentsBy: Reilly, Neil J.; Schmidt, Timothy W.; Kable, Scott H., JOURNAL OF PHYSICAL CHEMISTRY A, 110, 45, , 2006 Complicated vibronic structure – Two dimensional laser induced fluorescence spectroscopy: A powerful technique for elucidating rovibronic structure in electronic transitions of polyatomic molecules, Gascooke, Jason R.; Alexander, Ula N.; Lawrance, Warren D., JOURNAL OF CHEMICAL PHYSICS, 134, 18, , 2011

The 2Ds in the technique Counts λ em λ ex λ em λ ex Mol. Beam Laser light

Why use 2D on metal systems Saves time not having to record an emission (DF) for every band after doing excitation (LIF) and gives a complete “snap shot” of the systems. Due to the number of electrons in the systems of interest there is a high density of electronic states Facilitates finding polyatomics ( e.g. dioxides, carbenes, hyroxides, etc.)

Our Experimental Strategy Low Resolution 2D – Optimize production – Determine excitation wavelengths – Determine fluorescence pattern – Fluorescent lifetime High Resolution Excitation Measure rotationally resolved spectrum Determine field free constants Measurement Stark and Zeeman effects Magnetic properties Electric dipole moment

Chamber – Nozzle arrangement Mono CCD In house control software Change precursor gas or metal to change chemistry The Experimental Setup 10cm Ablation laser Excitation laser

Ex #1: Mn + N 2 O → MnO X6Σ+X6Σ+ B6Σ+B6Σ+

Ex. #2: Au + CH 4, CCl 4, OCS Au 2 X1Σg+X1Σg+ A0 u +

Ex #3: Ni + O 2 → NiO (narrow scan near cm -1 )

Part 2: Application to TMOs – The [19.04]O + -X 3  - band of NiO Of the first row transition metal oxides only NiO and MnO have no experimentally determined dipole moments. Rotationally resolved data available for band system in the red, but these bands are highly perturbed. – Friedman-Hill and Field, J. Mol. Spec. 155, ,1992 Only relatively low-resolution data is available for other bands in the blue. i.e. unresolved rotational structure observed. – Qin et al., Chinese J. Chem. Phys. 26, 5, , 2013 – Balfour et al., Chem. Phys. Lett. 385, , 2004 Many theoretical prediction of  el : – C. N. Sakellaris and A. Mavridis, J. Chem. Phys. 138, (2013) – A. Baranowska, M. Siedlecka, and A. J. Sadlej, Theor. Chem. Account (2007) 118, 959 – K. P. Jensen, B. O. Ross, and U. Ryde, J. Chem. Phys. 126, (2007) MethodR e (Å)μ el (Debye) WFT MRCI-L+DKH ±0.2 WFT (CASPT2)/CCSD(T) DFT- B3LYP TZVP DFT- BP86 TZVP DFT- PBE0 TZVP DFT- PBE TZVP DFT- BLYP TZVP

Ni+N 2 O → NiO (broad scan: cm -1 )

Ni+N 2 O → NiO (Narrow scan near cm -1 ) Low J lines perturbed.

X 3 Σ 0 - (ν=0) [19.04] Ω=0 + state Ni+N 2 O → NiO RP

532 nm NiO Ni Rod Stark Plate Filter 530±10 nm PMT High Resolution Setup 5%N 2 O in Ar Diode pumped ring laser

Measure and fit field-free, low J, lines. P(1) – P(6) R(0) – R(7) Fitting: 1.Hund’s case(a) representation for both X 3 Σ 0 an [19.04]0 + states 2. X 3 Σ 0 parameters fixed to microwave values. B ([19.04] )= (3) cm -1 The standard deviation of the fit is cm -1 No Perturbations ! Field-Free, High Resolution, NiO Kei-ichi Namiki and Shuji Saito, Chem. Phys. Lett. 252, , 1996

R(0), R(1) and P(1) lines chosen for optical Stark measurements. Field strengths from 1081 to 3243V/cm applied with parallel and perpendicular polarization. 24 Stark shifts were fit using the standard Stark Hamiltonian: H stark =-  el. E   el (X 3 Σ 0 - (ν=0)) = 4.43  0.04 D,  el ([19.04] )= 1.85  0.16 D Optical Stark Measurements

CoO (2.56 D/Å)< CuO (2.63 D/Å) < NiO (2.72 D/Å) NiO X 3 Σ 0 - electronic configuration = 1δ 4 3Π 4 8σ 2 9σ 2 4Π 2 CoO X 4 Δ i electronic configuration = 1δ 3 3Π 4 8σ 2 9σ 2 4Π 2 Vacancy in the 1δ leads to back bonding between the metal and oxygen. CuO X 2 P i has two important electronic configurations = The 10  orbital is the anti-bonding counterpart of the 8  orbital and is back polarized away from the Cu-O bond, thus reducing /R e Comparison to other First Row Transition Metal Oxides MoleculeR e (Å) (D) /R e (D/ Å) ScO(X 2 S + ) ± ± 0.04 TiO (X 3 D 1 ) ± ± 0.01 VO(X 4 S - ) ± ± CrO(X 5 P -1 ) ± ± 0.08 FeO(X 5 D 4 ) ± ± 0.02 CoO (X 4 D 7/2 ) ±0.05D2.56± 0.03 NiO (X 3 Σ ) ± ±0.02 CuO(X 2 P 3/2 ) ± ± 0.02 MnO? 1δ31δ3 8σ28σ2 9σ29σ2 3π43π4 4π24π2 Co O 2p 4 4s 2 3d 7 3d 8 NiCu 4s 1 3d 10 8σ28σ2 1δ41δ4 1δ41δ4 8σ28σ2 9σ19σ1 10σ 1 3π43π4 4π34π3 O 2p 4 Cu 4s 1 4p 1 3d 9 Cu O   tot  (10  ) ← e - 10  4π34π3

Application to other systems Metal carbides – FeC, FeC 2 and TiC, TiC 2 Gold chemistry – Zhang talk (TK09) Silicon Chemistry – Si 3 Singlet and triplet fluorescence, and intersystem crossing.

Acknowledgements NSF DOE