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52 matching references were found.

Simpson, R.L.; Helm, F.H.; Cook, T.M., The equation of state of perfluorododecane to 48 GPa, Rep., UCID-21710; Order No. DE89014306, 1989. [all data]

Helm, H.; Stephan, K.; Mark, T.D., Electron-impact ionization of Ar₂, ArKr, Kr₂, KrXe, and Xe₂, Phys. Rev. A:, 1979, 19, 2154. [all data]

Stephan, K.; Helm, H.; Kim, Y.B.; Seykora, G.; Ramler, J.; Grossl, M.; Mark, E.; Mark, T.D., Single and double ionization of nitrogen dioxide by electron impact from threshold up to 180 eV, J. Chem. Phys., 1980, 73, 303. [all data]

Helm, H.; Moller, R., Bound-free spectroscopy of Cs₂⁺, Phys. Rev. A:, 1983, 27, 2493. [all data]

Stephen, K.; Mark, T.D.; Futrell, J.H.; Helm, H., Electron impact ionization of (N₂)₂: Appearance energies of N₃⁺ and N₄⁺, J. Chem. Phys., 1984, 80, 3185. [all data]

Helm, H., The Mobilities and Equilibrium Reactions of Helium Ions in Helium at 77K, J. Phys. B, 1976, 9, 7, 1171, https://doi.org/10.1088/0022-3700/9/7/017 . [all data]

Helm, H., Formation of Xe3+ Ions in Xenon at Temperatures Between 210 and 293 K, Phys. Rev. A, 1976, 14, 2, 680, https://doi.org/10.1103/PhysRevA.14.680 . [all data]

Bordas, C.; Cosby, P.C.; Helm, H., Measurement of the lifetime of metastable triatomic hydrogen, J. Chem. Phys., 1990, 93, 9, 6303, https://doi.org/10.1063/1.458999 . [all data]

Bordas, C.; Helm, H., Predissociation of H_{3} near its ionization threshold induced by very weak electric fields, Phys. Rev. A, 1991, 43, 7, 3645, https://doi.org/10.1103/PhysRevA.43.3645 . [all data]

Bordas, M.C.; Lembo, L.J.; Helm, H., Spectroscopy and multichannel quantum-defect theory analysis of the np Rydberg series of H3, Phys. Rev. A, 1991, 44, 3, 1817, https://doi.org/10.1103/PhysRevA.44.1817 . [all data]

Cosby, P.C.; Helm, H., Photodissociation of Triatomic Hydrogen, Phys. Rev. Lett., 1988, 61, 3, 298, https://doi.org/10.1103/PhysRevLett.61.298 . [all data]

Helm, H., Observation of high-n Rydberg series (7n40) of the H_{3} molecule, Phys. Rev. Lett., 1986, 56, 1, 42, https://doi.org/10.1103/PhysRevLett.56.42 . [all data]

Helm, H., Measurement of the ionization potential of triatomic hydrogen, Phys. Rev. A, 1988, 38, 7, 3425, https://doi.org/10.1103/PhysRevA.38.3425 . [all data]

Lembo, L.J.; Helm, H., Observation of low-lying rydberg states of the triatomic hydrogen molecule, Chem. Phys. Lett., 1989, 163, 4-5, 425, https://doi.org/10.1016/0009-2614(89)85162-0 . [all data]

Lembo, L.J.; Helm, H.; Huestis, D.L., Measurement of vibrational frequencies of the H3 molecule using two-step photoionization, J. Chem. Phys., 1989, 90, 10, 5299, https://doi.org/10.1063/1.456434 . [all data]

Lembo, L.J.; Petit, A.; Helm, H., Vibrational autoionization in H_{3} and measurements of the symmetric-stretch frequency of the metastable 2p A_{2}^{''} state, Phys. Rev. A, 1989, 39, 7, 3721, https://doi.org/10.1103/PhysRevA.39.3721 . [all data]

Helm, H.; Stephan, K.; Mark, T.D., Electron-impact ionization of Ar₂, ArKr, Kr₂, KrXe, and Xe₂, Phys. Rev. A: Gen. Phys., 1979, 19, 2154-2160. [all data]

Cosby, P.C.; Helm, H.; Moseley, J.T., Observation of predissociated levels of CH⁺, Astrophys. J., 1980, 235, 52-56. [all data]

Helm, H.; Cosby, P.C.; Huestis, D.L., Laser predissociation spectroscopy of the f⁴Π_g state of O₂⁺, J. Chem. Phys., 1980, 73, 2629-2640. [all data]

Cosby, P.C.; Helm, H., Laser photofragment spectroscopy of NO⁺. I. Predissociation of the 2³Π state, J. Chem. Phys., 1981, 75, 3882-3893. [all data]

Helm, H.; Stephan, K.; Mark, T.D.; Huestis, D.L., Double ionization of van der Waals dimers: NeXe and ArXe, J. Chem. Phys., 1981, 74, 3844-3851. [all data]

Lee, L.C.; Helm, H.; Chang, J.S., O₂(b¹Σ_g⁺ → X³Σ_g^-) emission following HO₂ photodissociation by KrF laser photons, Chem. Phys. Lett., 1981, 81, 537-540. [all data]

Cosby, P.C.; Helm, H., Optical-optical double resonance spectroscopy of molecular ions, J. Chem. Phys., 1982, 76, 4720-4724. [all data]

Helm, H.; Cosby, P.C.; Saxon, R.P.; Huestis, D.L., Rotationally adiabatic treatment of Λ-doubling in CH⁺ A¹Π, J. Chem. Phys., 1982, 76, 2516-2523. [all data]

Helm, H.; Cosby, P.C.; Graff, M.M.; Moseley, J.T., Photofragment spectroscopy of CH⁺: laser excitation of shape resonances in the A¹Π state, Phys. Rev. A: Gen. Phys., 1982, 25, 304-321. [all data]

Helm, H.; Cosby, P.C., Laser photofragment spectroscopy of N₂⁺: evidence for predissociation of B²Σ_u⁺, J. Chem. Phys., 1982, 77, 5396-5405. [all data]

Helm, H.; Cosby, P.C.; Huestis, D.L., Observation of the 1²Π_u ← X²Σ_g⁺ system in Cs₂⁺, J. Chem. Phys., 1983, 78, 6451-6454. [all data]

Helm, H.; Huestis, D.L.; Dyer, M.J.; Lorents, D.C., Observation of the C(3/2) ← X(1/2) transition in XeF, J. Chem. Phys., 1983, 79, 3220-3226. [all data]

Helm, H.; Moller, R., Bound-free spectroscopy of Cs₂⁺, Phys. Rev. A: Gen. Phys., 1983, 27, 2493-2502. [all data]

Helm, H.; Jusinski, L.E.; Lorents, D.C.; Huestis, D.L., KrF laser excitation of the D(1/2)←X(1/2) transition of XeF, J. Chem. Phys., 1984, 80, 1796-1800. [all data]

Saxon, R.P.; Tuan, D.F.-t.; Helm, H., Ab initio investigation of the ³Π states of NO⁺, J. Chem. Phys., 1984, 80, 2648-2653. [all data]

Bjerre, N.; Kachru, R.; Helm, H., Three-photon double-resonance spectroscopy of autoionizing Rydberg states in H₂, Phys. Rev. A: Gen. Phys., 1985, 31, 1206-1208. [all data]

De Bruijn, D.P.; Helm, H., Dissociative decay of n = 3 levels in H₂. II. Excited by laser from the metastable c³Π_u^- state of H₂, Phys. Rev. A: Gen. Phys., 1986, 34, 3855-3864. [all data]

Bjerre, N.; Helm, H., High-resolution laser spectroscopy of H₂ in a fast beam, Chem. Phys. Lett., 1987, 134, 361-365. [all data]

Helm, H.; Cosby, P.C., Photodissociation measurement of rovibrational energies and populations of molecules in fast beams, J. Chem. Phys., 1987, 86, 6813-6822. [all data]

Keiding, S.; Bjerre, N.; Helm, H., The n=2,3 triplet Rydberg states of the HD molecule observed by fast neutral-beam photofragment spectroscopy, J. Chem. Phys., 1987, 86, 3050-3051. [all data]

Xu, E.Y.; Helm, H.; Kachru, R., Field ionization of high-lying states of H₂, Phys. Rev. Lett., 1987, 59, 1096-1099. [all data]

Xu, E.Y.; Tsuboi, T.; Kachru, R.; Helm, H., Four-photon dissociation and ionization of H₂, Phys. Rev. A: Gen. Phys., 1987, 36, 5645-5653. [all data]

Bjerre, N.; Keiding, S.R.; Lembo, L.J.; Helm, H., Autoionization of H₂ induced by a doubly excited triplet state, Phys. Rev. Lett., 1988, 60, 2465-2468. [all data]

Helm, H.; Cosby, P.C., Photoionization of N₂ E³Σ_g⁺, Phys. Rev. A: Gen. Phys., 1988, 38, 115-125. [all data]

Xu, E.Y.; Helm, H.; Kachru, R., Forced rotational autoionization of high-lying states of H₂, Phys. Rev. A: Gen. Phys., 1988, 38, 1666-1669. [all data]

Cosby, P.C.; Helm, H., Photofragment spectroscopy of O₂: excitation of the Schumann-Runge band system, J. Chem. Phys., 1989, 90, 1434-1439. [all data]

Xu, E.; Hickman, A.P.; Kachru, R.; Tsuboi, T.; Helm, H., Photoelectron spectroscopy of vibrationally excited H₂ (E, F¹Σ_g⁺), Phys. Rev. A: Gen. Phys., 1989, 40, 7031-7038. [all data]

Cosby, P.C.; Helm, H.; Larzilliere, M., Photofragment spectroscopy of HF⁺, J. Chem. Phys., 1991, 94, 92-105. [all data]

Helm, H.; Dyer, M.J.; Bissantz, H., Simplification of photoelectron spectra of H₂ in intense laser fields, Phys. Rev. Lett., 1991, 67, 1234-1237. [all data]

Helm, P.A.; Jantunen, L.M.M.; Bidleman, T.F.; Dorman, F.L., Complete separation of isomeric penta- and hexachloronaphthalenes by capillary gas chromatography, J. Hi. Res. Chromatogr., 1999, 22, 11, 639-643, https://doi.org/10.1002/(SICI)1521-4168(19991101)22:11<639::AID-JHRC639>3.0.CO;2-T . [all data]

Haines, W.E.; Helm, R.V.; Bailey, c.W.; Ball, J.S., Purification and properties of ten organic sulfur compounds, J. Phys. Chem., 1954, 58, 270-278. [all data]

Morris, J.C.; Lanum, W.J.; Helm, R.V.; Haines, W.E.; Cook, G.L.; Ball, J.S., Purification and Properties of Ten Organic Sulfur Compounds, J. Chem. Eng. Data, 1960, 5, 112-6. [all data]

Helm, R.V.; Lanum, W.J.; Cook, G.L.; Ball, J.S., Purification and Properties of Pyrrole, Pyrrolidine, Pyridine and 2-Methylpyridine, J. Phys. Chem., 1958, 62, 858. [all data]

Haines, W.E.; Helm, R.V.; Cook, G.L.; Ball, J.S., Purification and Properties of Organic Sulfur Compounds, J. Phys. Chem., 1956, 60, 549-55. [all data]

Thompson, C.J.; Coleman, H.J.; Helm, R.V., The purification and some physical properties of nitromethane, J. Am. Chem. Soc., 1954, 76, 3445-6. [all data]

Haines, W.E.; Helm, R.V.; Bailey, C.W.; Ball, J.S., Purification adn Properties of Ten Organic Sulfur Compounds, J. Phys. Chem., 1954, 58, 270-8. [all data]