Forecasting two-photon absorption based on one-photon properties Nikolay Makarov, Department of Physics, Montana State University Mikhail Drobizhev, Zhiyong Suo, Aleks Rebane E. Scott Tarter, Benjamin D. Reeves, Brenda Spangler Fanqing Meng, Charles W. Spangler Craig J. Wilson, Harry L. Anderson Department of Physics, Montana State University, Bozeman, MT Sensopath Technologies, Inc., Bozeman, MT MPA Technologies, Inc., Bozeman, MT Department of Chemistry, University of Oxford, Mansfield, Oxford, UK

Outline Motivation Experiments Calculations Conclusions

Motivation: Why to predict? l N H C l N C H N N C Which one is better? Why?

Motivation: What can quantum chemistry do? m, Em, m C. Katan, S. Tretiak, M.H.V. Werts, A.J. Bain, R.J. Marsh, N. Leonczek, N. Nicolaou, E. Badaeva, O. Mongin, M. Blanchard-Desce, “Two-photon transitions in quadrupolar and branched chromophores: experiment and theory”, J. Phys. Chem. B 2007, 111, 9468-9483

Experiments: Setup Jobin Yvon Triax 550 sample Laser system L2 USB Coherent VERDI 6 4W CW 532nm L2 Coherent MIRA 900 0.5W 795nm 150fs Wavelength control Hamamatsu Streak Camera C5680 Coherent LEGEND Regen. Amplifier 1.1W 1kHz 795nm 150fs Intensity control TOPAS-C 0.3W 1kHz 125fs USB Serial Digital Oscilloscope Ref. Channel DAQ GPIB CCD camera control and DAQ PC LabView Filter wheel Corre- lator Ref. detector FROG OSA L1 Pulse characterization LN CCD sample 300 600 1200 l/mm-1 F1 M1 Jobin Yvon Triax 550 Perkin-Elmer Lambda900 Spectrophotometer Perkin-Elmer LS 50B Luminescence Spectrometer

Experimental Results 11 3 1 5 10 14 , M-1cm-1 s2, GM Frequency, cm-1 Wavelength, nm s2, GM 11 , M-1cm-1 1.25104 2.5104 3.75104 5104 3 1104 2104 3104 4104 Frequency, cm-1 1 5 10 14

Second order perturbation theory: Calculations: How to? Second order perturbation theory: 1 Local field factors: Lorentz Onsager Dipole moments: Solvatochromic shifts Linear absorption, fluorescence Molecule density Fluorescence anisotropy

Calculations: Results 100 200 300 7 2 11 6 9 1 8 5 4 3 12 10 2, GM 100 200 300 2, GM 11 2 12 10 5 4 1 6 9 7 8 3 14 R2 For molecule density (=1) For anisotropy 2(a) 2(b) fL 0.8 3.3 1.4 fO 0.6 1.8 0.9

Conclusions Acknowledgements See poster for details We show that the perturbation theory applied for two-level system quantitatively predicts the 2PA cross sections in dipolar molecules, provided that the necessary molecular parameters such as transition- and permanent dipole moments are independently measured. In most cases, the discrepancy between theory and experiment was less than 20%, and always less than 50%. This is the first time that such direct quantitative correspondence is demonstrated for a wide range of dipolar molecules. The overall significance of this work demonstrates a practical way how a set of relatively straightforward linear spectroscopic measurements can be used to study and predict nonlinear 2PA properties. Acknowledgements The work was supported by AFOSR. See poster for details