William Klemperer

A major theme of current research in Professor Klemperer's group is geometric and electronic structure of van der Waals molecules and weakly bound complexes. We can determine the nature of weak bonding with the same detail and precision as exists for the strong chemical bonds. The experimental studies utilize molecular beam techniques for producing spectroscopic data in low effective temperature (5K) supersonic jets, a virtually new state of matter, the frozen gas. Analysis of the spectra involves modeling of internal dynamics in non-rigid molecular systems and testing theoretical potential energy functions and electronic charge distributions. Of the many types of weak bonds that frequently occur, hydrogen bonding is exceptional. We are concerned with proton mobility as well as the location of atoms.

A related topic is the study of highly excited vibrational states of simple molecules. The behavior of polyatomic molecules at energies in which many states exist is of continuing current concern. Thus the basis for such fundamental processes as energy flow/localization, isomerization paths, photodissociation time scales may be determined. The dynamical behavior of systems at high energy is studied spectroscopically. The high spectral resolution readily available today permits detailed probing of a variety of systems. The more complex the spectrum, the richer is the phenomena, but the more difficult is its characterization. There are many opportunities for the development of novel experiments and their theoretical interpretations.

A major portion of the interstellar medium is the cold (10K) low density (10e-16 atm) region between stars. Chemistries of the interstellar medium are novel in that they occur in general, at these extreme low temperatures and densities, with relatively high efficiencies. The ever increasing astronomical observations, primarily radio astronomy, provide a broad source of unique information against which tests of our understanding of fundamental chemistry and molecular physics may be made. Our research involves primarily modeling the kinetic behavior of this fascinating region.

Selected Publications

1. "Water Hydrogen Bonding: The Structure of the Water-Carbon Monoxide Complex," D. Yaron, K.I. Peterson, D. Zolandz, W. Klemperer, F.J. Lovas and R.D. Suenram, J. Chem. Phys., 92, 7095 (1990).

2. "On the Fallibility of Variational Calculations: Ab initio vs. Empirical Potential Energy Functions for HCN," A.M. Smith, W. Klemperer and K.K. Lehmann, J. Chem. Phys., 94, 5040 (1991).

3. "Preliminary Structural Characterization of Complexes of Cyanogen: NH3-NCCN and (NCCN)2," I. Suni, S. Lee and W. Klemperer, J. Phys. Chem., 95, 2859 (1991).

4. "Microwave and Submillimeter Spectroscopy of Ar-HN3 States Correlating with Ar + NH3 (j=1, |K|= 1)," E. Zwart, H. Linnartz, W.L. Meerts, G.T. Fraser, D.D. Nelson, Jr. and W. Klemperer, J. Chem. Phys., 95, 793 (1991).

5. "Model Calculations on the Ground Vibrational State of Ar-HCN," D. Yaron and W. Klemperer, J. Chem. Phys., 95, 1907 (1991).

6. "High Resolution Spectrum ot the v = 1 State of ArHCN," A.L. Cooksy, S. Drucker, J. Faeder, C.A. Gottlieb and W. Klemperer J. Chem. Phys., 95, 3017 (1991).

7. "The Rotational Spectrum, Internal Rotation, and Structure of H2O-NCCN and D2O-NCCH," S. Lee, I.I. Suni and W. Klemperer, J. Chem. Phys., 96, 5577 (1992).

8. "The van der Waals Potential-Energy Surfaces and the Structures of ArCIF and ArCI2," F.-M. Tao and W. Klemperer, J. Chem. Phys. 97, 440 (1992).

9. "Water in Weak Interactions: The Structure of the Water-Nitrous Oxide Complex," D. Zolandz, D. Yaron, K.I. Peterson and W. Klemperer, J. Chem. Phys. 97, 2861 (1992).

10. "Intermolecular Interactions," W. Klemperer, Science 257, 887 (1992).

11. "Angular-Radial Coupling in the Tunneling Motion of (HCCH)2," I.I. Suni and W. Klemperer, J. Chem. Phys. 98, 988 (1993).

12. "The One-Atom Cage Effect: Continuum Processes in I2-Ar Below the B State Dissociation Limit," M.L. Burke and W. Klemperer, J. Chem. Phys. 98, 1797 (1993).

13. "On the Use of Bond Functions in Molecular Calculations," F.-M. Tao, J. Chem. Phys. 98, 2481 (1993).

14. "Observation of ArHF(3000) and Its Combination Modes by Laser-Induced Fluorescence," H.-C. Chang and W. Klemperer, J. Chem. Phys. 98, 2497 (1993).

15. "The Use of Midbond Functions for the Calculations of the Asymmetric Interaction Potentials of He-Ne and He-Ar," F.-M. Tao, J. Chem. Phys. 98, 3049 (1993).

16. "Can Molecules Have Permanent Electric Dipole Moments?," W. Klemperer, K.K. Lehmann, J.K.G. Watson and S.C. Wofsy, J. Phys. Chem. 97, 2413 (1993).

17. "Spectroscopic Characterization of the Lowest Sigma and Pi Bending States of ArHCN," S. Drucker, A.L. Cooksy and W. Klemperer, J. Chem. Phys. 98, 5158 (1993).

18. "The Potential to Surprise," William Klemperer, Nature 362, 698 (1993).

19. "Efficiency and Mechanism of Electronic Predissociation of B State I2-Ar," M.L. Burke and W. Klemperer, J. Chem. Phys. 98, 6642 (1993).

20. "State-Specific Vibrational Predissociation and Interconversion Tunneling Quenching at 3v1 and 3v2 of (HF)2," H-C. Chang and W. Klemperer, J. Chem. Phys. 98, 9266 (1993).

21. "The Counterpoise Method and Bond Functions in Molecular Dissociation Energy Calculations," F.-M. Tao, Chem. Physics Letters 206, 560 (1993).

22. "A Search for Nuclear Quadrupole Effects on the Dipole Moment of Methyl Iodide," D. Zolandz, S.N. Yaliraki, W. Klemperer, S. Carocci, P. Minguzzi, M. Tonelli and A.DiLieto, J. Mol. Spectr. 160, 351 (1993).

23. "Ab Initio Search for the Equilibrium Structure of the Ammonia Dimer", F.-M. Tao and W. Klemperer, J. Chem. Phys. 99, 5976 (1993).

24. "Dipole Moment Analysis of Excited van der Waals Vibrational States of ArH35Cl," A.L. Cooksy, M.J. Elrod, R.J. Saykally and W. Klemperer, J. Chem. Phys. 99, 3200 (1993).

25. "The Ar-HF Intermolecular Potential: Overtone Spectroscopy and ab initio Calculations," H.-C. Chang, F.-M. Tao, W. Klemperer, C. Healey and J. Hutson, J. Chem. Phys. 99, 9337 (1993).

26. "The Vibrational Second Overtones of HF Dimer: A Quartet," H.-C. Chang and W. Klemperer, J. Chem. Phys. 100, 1 (1994).

27. "A New Approach to the Efficient Basis Set for Accurate Molecular Calculations: Applications to Diatomic Molecules," F.-M. Tao, J. Chem. Phys. 100, 3645 (1994).

28. "An ab initio Study of the HNCN Radical", F.-M. Tao, W. Klemperer, M.C. McCarthy, C.A. Gottlieb and P. Thaddeus, J. Chem. Phys. 100, 3691 (1994).

29. "An Accurate ab initio Potential Energy Surface of the He-H2 Interaction," F.-M. Tao, J. Chem. Phys. 100, 4947 (1994).

30. "Accurate ab initio Potential Energy Surfaces of Ar-HF, Ar-H2O, and Ar-NH3," F.-M. Tao and W. Klemperer, J. Chem. Phys. 101, 1129 (1994).

31. "Characterization of N2HF at 3n1 HF Stretch," S.N. Tsang, H.-C. Chang and W. Klemperer, J. Phys. Chem. 98, 7313 (1994).

32. "Ab initio Potential Energy Surface and Dynamics of He-CO," F.-M. Tao, S. Drucker, R.C. Cohen and W. Klemperer, J. Chem. Phys. 101, 8680 (1994).

33. "Current Themes in Microwave and Infrared Spectroscopy of Weakly Bound Complexes," K.R. Leopold, G.T. Fraser, S.E. Novick, and W. Klemperer, Chem. Rev. 94, 1807 (1994).

34. "High-Overtone Spectroscopy and Photodissociation of Hydrogen Fluoride Complexes," H.-C. Chang and W. Klemperer, Faraday Discuss. 97, 95 (1994).

35. "Vibrational Predissociation of HFHCl by Overtone Excitation of HF," R. Mollaaghababa, H.-C. Chang and W. Klemperer, Can. J. Phys. 72, 963 (1994).

36. "Bound States of HeHCN: Ab Initio Calculation and High-Resolution Spectroscopy," S. Drucker, F.-M. Tao and W. Klemperer, J. Phys. Chem. 99, 2646-2655 (1995).

37. "Intermolecular Potential and Rovibrational Energy Levels of the Ar Complexes with HCN and HCCH," F.-M. Tao, S. Drucker and W. Klemperer, J. Chem. Phys. 102, 7289-7297 (1995).

38. "Dependence of the Interaction Potentials of Ar-HF and N2-HF on HF Bond Length," H.-C. Chang, F.-M. Tao, S.N. Tsang and W. Klemperer, J. Chin. Chem. Soc. 42, 141-148 (1995).

39. "The HeCl2 Potential: Atom-Atom and ab initio Compared to Experiment," S.S. Huang, C.R. Bieler, K.C. Janda, F.-M. Tao, W. Klemperer, P. Casaecchia, G.G. Volpi, N. Halberstadt, J. Chem. Phys. 102, 8846-8854 (1995).

40. "Some Spectroscopic Reminiscences," W. Klemperer, Ann. Rev. Phys. Chem. 46, 1-26 (1995).

41. "On the Possibility of Coherently Stimulated Recombination and Cosmological Structure Generation; Recombination Instability," W. Klemperer, X. Luo, R. Rosner and D.N. Schramm, PNAS 92, 6166-6170 (1995).

42. "On the Possibility of Coherently Stimulated Recombination and Cosmological Structure Generation: Cosmological Consequences," D.N. Schramm, R. Rosner, X. Luo, and W. Klemperer, PNAS 92, 6171-6174 (1995).

43. "Ab Initio Potential Energy Surface for the HCl Dimer," F-.M. Tao and W. Klemperer, J. Chem. Phys. 103, 950-956 (1995)

44. "Structures, Electronic Properties, and Isomerization of HCCCO Radical," A.L. Cooksy, F.-M. Tao, W. Klemperer and P. Thaddeus, J. Phys. Chem. 99, 11095-11100 (1995).

45. "A Phenomenological Model for the Vibrational Dependence of Hydrogen Interchange Tunneling in HF Dimer," H.-C. Chang and W. Klemperer, J. Chem. Phys. 104, 7830-7835 (1996).

46. "Structure, Binding Energy and Equilibrium Constant of the Nitric Acid-Water Complex," F.-M. Tao, K. Higgins, W. Klemperer and D. Nelson, Geophy. Res. Let. 23, 1797-1800 (1996).

47. "Intermolecular State Dependence of the Vibrational Predissociation of N2HF," S.N. Tsang, C.-C. Chuang, R. Mollaaghababa, W. Klemperer and H-C. Chang, J. Chem. Phys. 105, 4385- 4387 (1996).

48. The Chemistry of the Interstellar Medium as Revealed by Spectroscopy, K. Klemperer, Proceedings, The Royal Institution, London, 209-244 (1997).

49. "Reassignment of the 11, 537 cm-1 Band of Hydrogen Fluoride Dimer and Observation of the Intermolecular Combination Mode 3 vl + v4," C.C. Chuang, S.N. Tsang and W. Klemperer, J. Phys. Chem. A. 101, 6702-6708 (1997).

50. "Laser-Induced Fluorescence Spectroscopy of Ar2HF at vHF = 3: An Examination of Three-Body Forces," C.-C. Chuang, S.N. Tsang, J.G. Hanson, W. Klemperer and H.-C. Chang, J. Chem. Phys. 107, 7041-7056 (1997).

51. "Vibrational Predissociation of an Inert Gas Cluster Containing an Active Molecule: vHF=3 Spectrum of Ar3HF," C.-C. Chuang, S.N. Tsang, W. Klemperer and H.-C. Chang, J. Chem. Phys. 109, 484-491 (1998).

52. "The Intermolecular Potential Between an Inert Gas and a Halogen: Prediction and Observation of Transitions Between the Linear and T-Shaped Isomers of HeCIF," K. Higgins, F.-M. Tao and W. Klemperer, J. Chem. Phys. 109, 3048-3061 (1998).

53."Vibrational Predissociation Dynamics of ArHF (3000) and (3110): Lifetimes and HF Product State Distributions," C.-C. Chuang, S.N. Tsang, W. Klemperer and H-C. Chang, J. Chem. Phys. 109, 8836-8841 (1998).

54. "The Intermolecular Potential of He-OCS," K. Higgins and W. Klemperer, J. Chem. Phys. 110, 1383-1388 (1999).

55. Dynamics of Linear and T-Shaped Ar-I2, Dissociation upon B-X Optical Excitation: A Dispersed Fluorescence Study of the Linear Isomer, A.E. Stevens-Miller, C.-C. Chuang, H.C. Fu, K.J. Higgins and W. Klemperer, J. Chem. Phys. 111, 7844-7856 (1999).

56. The CO Cameron Band Emission in the Red Rectangle, M. Yan, A. Dalgarno, W. Klemperer and A.E.S. Miller, Mon. Not. R. Astron. Soc. 313, L17-L18 (2000).

57. Weak Bond Stretching for Three Orientations of Ar-HF at nHF=3, C.-C. Chuang, K.J. Higgins, H.C. Fu and W. Klemperer, J. Chem. Phys. 112, 7022-7031 (2000).

58. The Dependence of Intermolecular Interactions Upon Valence Coordinate Excitation: The nHF = 4 Levels of ArHF, C.-C. Chuang and W. Klemperer, J, Chem. Phys. 113, 4116-4123 (2000).

59. The Chemistry of Interstellar Grains and the SWS-ISO Spectra, F. Scappini, H. Smith and W. Klemperer, Italian Physical Society, Conference Proceedings Vol. 67, Workshop: Molecules in Space and in the Laboratory, 55-61 (2000).

60. Spectra of N2-HF from Symmetry-Adapted Perturbation Theory Potential, P. Jankowksi, S.N. Tsang, W. Klemperer, and K. Szalewicz, J. Chem. Phys. 114, 8948-8963 (2001).

61 Spectroscopy of van der Waals Molecules: Isomers and Vibrational Predissociation, W. Klemperer, C.C. Chuang, K.J. Higgins, A. Stevens-Miller, H.C. Fu, Can. J. Phys. 79, 101-108 (2001).

62. The Complex Story of H2,,, William Klemperer, Science 293, 815-816 (2001).