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Novel photonic materials Manthos G. Papadopoulos PowerPoint Presentation
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Novel photonic materials Manthos G. Papadopoulos

Novel photonic materials Manthos G. Papadopoulos

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Novel photonic materials Manthos G. Papadopoulos

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  1. Novel photonic materials Manthos G. Papadopoulos Institute of Organic and Pharmaceutical Chemistry. National Hellenic Research Foundation 48 Vas. Constantinou Av. Athens 11635

  2. We will consider a series of derivatives, which have interesting linear and nonlinear optical properties and possible applications in the photonic industry • Unifying features of this work: • Molecules with large NLO properties • and how these can be interpreted • Discovery of mechanisms in order • to modify the L&NLO properties

  3. More specifically, we shall comment on the results • of three projects: • The L&NLO properties of derivatives • involving noble gas atoms • The L&NLO properties of [60]fullerene • derivatives • 3. The structure and properties of Ni-dithiolenes

  4. Definition of the electric properties E = E(0) -μαFα - (1/2)ααβFαFβ - (1/6)βαβγFαFβFγ - (1/24)γαβγδFαFβFγFδ - ... μα : Dipole moment ααβ: Polarizability βαβγ: First hyperpolarizability γαβγδ:Second hyperpolarizability

  5. Why the L&NLO properties are important: • Theory • Study of L&NLO processes (e.g. Kerr effect) • Intermolecular interactions • Applications • Design and study of NLO materials (optical processing of information, optical computing)

  6. Noble gas derivatives Definition of the project: We consider insertion of a noble gas atom, Ng, in the chemical bond A-B, leading to A-Ng-B. Specific examples we will consider involve insertion of: Arin HFleading toHArF Xe in HCnH leading to HXeCnH Xe in AuF lading to AuXeF

  7. Why are the noble gas derivatives interesting and significant? • It is amazing what a noble gas atom, in the middle of a single bond can do, for example it leads to: • large NLO properties, • significant charge transfer etc Which is the expanation?

  8. HArF A. Avramopoulos, H. Reis, J. Li and M. G. Papadopoulos, J. Am. Chem. Soc., 126, 6179 (2004).

  9. Properties of noble gases • Synthesis of HArFa (argon fluoro-hydride) [first covalent neutral cond. argon der.] photolysis of HF in solid argon matrix Point of interest: The effect of Ar on the NLO properties of the resulting derivative a. L. Khriachtchev et al., Nature, 406, 874 (2000)

  10. μz αzz βzzz Pol HF MP2 CCSD(T) aug-cc-pV5Z HF MP2 3.139 2.691 2.578 3.085 2.653 37.61 55.37 59.80 37.80 54.01 -597.8 -1220.9 -1418.1 -578.7 -1102.5 The dipole moment, polarizability and first hyperpolarizability of HArF (in a.u.)

  11. μgg: ground state dipole moment μee: excited state dipole moment μge: transition dipole moment Εge: transition energy Rationalization ofβzzz Comparison of HArF withHF μgg: 3.473/0.745 a.u. μee: -0.814/-0.907 a.u. μge: 1.419/-0.611a.u. Εge: 0.276/0.570 a.u. Method: HF/Pol, CIS/Pol All the above properties contribute so that βzzz of HArF is much larger than that of HF

  12. Reliabity of TSM HArF βzzz=-561.5 a.u. HF/Pol -340.7 a.u. TSM HF βzzz=-7.4 a.u. HF/Pol -5.7 a.u. TSM • Reliability of TSM • Large effect of Ar

  13. HF…Ar van der Waals complex μz=0.983 a.u. (3.473 a.u.) αzz=19.11 a.u. (34.25 a.u.) βzzz= -35.09 a.u. (-561.5 a.u.) ratio=16 Charge of Ar: 0.02 (0.56) ratio=28 Method: HF/Pol

  14. Comparison of HArF with C6H6 Αzz = 44.74 a.u. (34.25 a.u.) Method: MP4[SDQ] P-nitro-aniline βzzz = 797.5 a.u. ( -561.5 a.u.) Method: HF/Pol

  15. The linear and nonlinear optical properties of derivatives with inserted Xe

  16. The first Xe derivative was reported by Bartlet in 1962 [Proc. Chem. Soc., 218(1962)] • A large number of Xe compounds have been reported since then

  17. HXeF, AuXeF, XeAuF F. Holka,A. Avramopoulos, O. Loboda, V. Kellö, M. G. Papadopoulos, Chem. Phys. Letters, 472, 185 (2009)

  18. Points of interest: • Effect of Xe • Comparison of H with Au HXeF, AuXeF: not synthesized yet XeAuF: several NgMF have been synthesized Ng: Ar, Kr, Xe M: Cu, Ag, Au X: F, Cl, Br

  19. Bonding: Xe - Au bond: covalent [1] Au - Xe [AuXeF] bond: partially covalent (AXe)+ F-: significant charge transfer A= H, Au The barrier height AuXeF: 119 kJmol-1 separates the global minimum (AuF+Xe) from the local minimum 1. S. A. Cook and M. C. L. Gerry, J. Am Chem. Soc.126, 17000 (2004).

  20. NBO charges Method: HF/aug-cc-pVQZ • Similar charges on F • Quite different charges for Xe of XeAuF and AuXeF

  21. L&NLO properties Method: CCSD(T) Basis set: aug-cc-pVQZ ECP: Au(60), Xe(28) The position of Xe has a great effect on αzz and βzzz

  22. βzzz(AuXeF) / βzzz (AuF) = 6.0 • βzzz(XeAuF) / βzzz (AuF) = 0.7 Method: CCSD(T) Basis set: aug-cc-pVQZ • βzzz(HXeF) / βzzz (HF) = 57.0 Xe may greatly affect βzzz

  23. Relativistic contribution: AuXeF Methods: CCSD(T), Douglas-Kroll Basis sets: PolX, PolX_DK βzzz = great effect of relativistic contribution

  24. Novel compounds derived by Xe inserted into HC2H and HC4H: L&NLO properties A.Avramopoulos, L. Serrano-Andres, J. Li, H. Reis and M. G. Papadopoulos, J. Chem. Phys., 127, 214 (2007).

  25. Preparation HXeC2H and HXeC2XeH: They are prepared in a low-temperature Xe matrix using UV photolysis of C2H2 and subsequently annealing at 40-45K [JACS, 125, 4696 (2003)] HXeC4H: Tanskanen et al. reported its preparation [JACS, 125, 16361 (2003)] HC2XeC2H: Ansbacher et al. predicted that the diacetylide Xe exists as a metastable chemically-bound compound [PCCP, 8, 4175 (2006)]

  26. Resonance structures of HXeC2H Structures Weight (%)a H–Xe+C–CH (I) 44 H·Xe·CCH (II) 26 H–Xe+–CCH (III) 14 H–Xe2+C–CH (IV) 11 H+XeC–CH (V) 5 Method:CASVB(6,4)/3-21G*

  27. Charge transfer in HXeC2H • Intra-molecular • Inter-molecular

  28. NBO Charge Distribution • 1 and 2 Xe atoms: • Approx. the same charge • The chain length does not appear to have an effect

  29. 1 Xe atom • End:0.79 e • Middle:1.02 e • 3 Xe atoms: • The middle one has much larger charge Method:HF/aug-cc-pVZ

  30. Inter-molecular charge transfer • {Xe matrix}/HXeC2H • Two models • 6 Xe atoms octahedrally placed around HXeC2H • A1A2=7.56 a.u. • A2A3=9.45 a.u. • Method:MP2/aug-cc-pVDZ

  31. (b) 8 Xe atoms arranged in a cube A1A2=15.12 a.u.

  32. NBO analysis: insignificant CT takes place from the Xe environment to HXeC2H: 0.02e in the first model and 0.002e in the second model

  33. HXeC2H HC2H The effect of Xe Is significant Method:CCSD(T)/B1

  34. HXeC2XeH HXeC2H The effect of 1 and 2 Xe atoms Method: MP2/B1

  35. The effect of Xe in connection with effect of the chain length H2C2H H2C4H Δγzzzz = 30 000 au (approx.) H2XeC2H H2XeC4H Δγzzzz = 340 000 au (approx.)

  36. H-Xe-CC-CC-H γzzzz =111 190 a.u • H-CC-Xe-CC-H γzzzz =28 488 a.u. • H-CC-CC-H γzzzz = 31 224 a.u. • Xe leads to a reduction of γzzzz ! • The position of Xe has a significant effect on γzzzz • Method: MP2/aug-cc-pVDZ

  37. Decomposition channels of HXeC2H H+ Xe + C2H HXeC2H Xe + HC2H 34 kcalmol-1 104 kcalmol-1 The barrier to this exothermic reaction is very high, 64.6 kcalmol-1 and prevents the molecule from dissociation T. Ansbacher et al., PCCP, 8, 4175 (2006)

  38. Vibrational properties Example: HXeC2H αpvzz = [μ2](0,0)=60.13 a.u Vibrational Modes: H-Xe: 1681cm-1 [μ2](0,0)=13.1 a.u Xe-C: 313 cm-1 [μ2](0,0)=46.8 a.u The other modes have a negligible contribution (0.23 a.u.) Method:MP2/aug-cc-pVDZ

  39. βpvzzz = [μα](0,0) = -835 a.u. Vibrational Modes: H-Xe: 1681cm-1 [μα](0,0)=1212 a.u Xe-C: 313 cm-1 [μα](0,0)=-2079a.u The other modes have a very small contribution (32 a.u.) Method:MP2/aug-cc-pVDZ

  40. Local field effect • The Xe derivatives have been synthesized in a Xe matrix • Thus it would be useful to compute the effect of the Xe environment on the L&NLO properties • Example: HXeC2H • The discrete local field approximation has been applied • Only the dipole and induced dipole interactions between HXeC2H and the Xe environment are considered

  41. Local field expression: , Where N is the number of molecules in the cell Vcell is the volume of the cell ε0is the permitivity of vacuum α,β,γ are the Cartesian components Fk’α is the permanent local field effect on molecule k’ due to the surrounding molecules μk’βis the dipole moment of the free molecule k’ αk’αβis the polarizability of the free moleculek’ L(11) is the Lorentz-factor tensor

  42. Y Z X Model: Cubic closed packed with dimensions a=b=c=24.8092 Å It involves 255 Xe atoms

  43. Employed data: HXeC2H: Dipole moment and polarizability of at the CCSD(T) level and Xe: experimental polarizability value (27.10 au) Results: Local field: Fz=-4.4x10-3 au μz:50.5% αzz:2.5% βzzz:20.2% γzzzz: 12.7% Changes of properties

  44. Interpretation of the results Insertion of Xe in HCnH leads to a large increase of γzzzz For example: γzzzz(HXeC2H)=38740 au γzzzz(HC2H)=3380 au Ratio=11.5 Why? Method: CASSCF/CASPT2 Basis set:ANO-RCC Xe:7s6p4d2f1g C:4s3p2d1f H:3s2p1d CASSSF(10,14)

  45. The computations have shown that insertion of Xe leads to: (a) Excited states of lower energy (b) An electronic spectrum which is more dense in low lying states (c) Many non-zero contributions to the transition dipole moment matrix

  46. The SOS model • The NLO properties are: • proportional to products of TDM matrix elements and • inversely proportional to products of energy differences • Therefore an enhancement to NLO properties is expected

  47. SOS computed properties HC2H HXeC2H αzz = 11.07 au αzz = 26.51 au γzzzz = 3473au γzzzz = 9102 au The SOS model reflects the expected trend

  48. On the electronic structure of H-Ng-Ng-F (Ng=Ar, Kr, Xe) and the L&NLO properties of HXe2F A.Avramopoulos, L. Serrano-Andre, J.Li, M. G. Papadopoulos, J. Chem. Theory Comput. 6, 3365 (2010).

  49. Questions: The diradical character of HNg2F and the L&NLO properties Methods: CASVB, MS-CASPT2, CCSD(T)

  50. Electronic ground state description HArArF: 38%σ2 + 56%σσ* HΚrΚrF: 53%σ2 + 39%σσ* HΧeXeF: 58%σ2 + 35%σσ* Increase of the closed shell character: Xe > Kr > Ar Method: MS-CASPT2/ANO