XIX. <i>Further experiments on positive rays</i>

Thomson, J. J.

doi:10.1080/14786440808637325

Cited by 153 publications

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“…Now 100 years after its discovery by Thomson [1,2] in an early form of mass spectrometry, it is still of particular interest for astrophysical, theoretical and experimental research. The first laboratory spectrum was recorded by Oka in 1980, initiating the astronomical search [3].…”

Section: Introductionmentioning

confidence: 99%

Visible transitions from ground state H ₃ ⁺ measured with high-sensitivity action spectroscopy

Berg

Wolf

Petrignani

2012

Phil. Trans. R. Soc. A.

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We report on the recent observation of new spectral lines of cold H + 3 ions lying well in the visible spectral region. Transitions from the two lowest ro-vibrational levels to final levels up to 16 700 cm −1 , almost half way to the dissociation limit, have been measured, involving up to eight vibrational quanta. The observed transitions are more than six orders of magnitude less intense than the n 1 2 fundamental band and yet another order of magnitude weaker than reached by previous sensitive action spectroscopy in the nearinfrared region. The measurements were carried out in a cryogenic 22-pole ion trap with H + 3 ions cooled to their lowest rotational levels by helium buffer gas. Laser-induced chemical reactions lead to the formation of ArH + ions detected with single-ion sensitivity. These visible measurements, together with the previous near-infrared measurements, have helped to further develop empirically corrected calculations and have provided essential benchmarks for new ab initio calculations that now reach a spectroscopic accuracy of 0.1 cm −1 on average up to the highest observed transition. Highly sensitive action spectroscopy and the attained high-accuracy predictions will enable us to find and measure transitions even further into the visible region of H + 3 , paving the way towards the dissociation limit.

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Section: Introductionmentioning

confidence: 99%

Visible transitions from ground state H ₃ ⁺ measured with high-sensitivity action spectroscopy

Berg

Wolf

Petrignani

2012

Phil. Trans. R. Soc. A.

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“…Two of the main areas of interest to theorists are in accurate calculations of the equilibrium energy and internuclear distance that can be used to test and compare different calculational methods and in improved ground-state potential-energy surfaces that would be helpful to experimentalists attempting to assign labels to H3+ rovibrational transitions. Since its original discovery by Thomson in 1912,1 experiments have confirmed the work of a long line of theorists 2 -" that the equilibrium configuration is an equililateral triangle 12 and that its energy is E = -1.33 ± 0.01 hartree. 13 • 14 Notwithstanding its frequent role in testing new calculational methods and theories, the energy of the ground state continues to be lowered significantly by new calculations.…”

Section: Introductionmentioning

confidence: 67%

Gaussian functions in Hylleraas-configuration interaction calculations. V. An accurate a b i n i t i o H+3 potential-energy surface

Frye

Preiskorn

Lie

et al. 1990

The Journal of Chemical Physics

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Accurate a b i n i t i o potential energy computations for the H4 system: Tests of some analytic potential energy surfaces J. Chem. Phys. 95, 4331 (1991); 10.1063/1.461757 Gaussian functions in Hylleraasconfiguration interaction calculations: Potential curves for the e 3∑+ u and the f 3∑+ u states of hydrogen J. Chem. Phys. 92, 4941 (1990); 10.1063/1.457711 Potentialenergy surfaces for Pt2+H and Pt+H interactions J. Chem. Phys. 92, 541 (1990); 10.1063/1.458457 Gaussian functions in Hylleraasconfiguration interaction calculations. II. Potential curves for the b 3Σ+ u and the e 3Σ+ u states of hydrogenThe near-equilibrium potential-energy surface of the 'A ; ground state ofH3+ has been calculated at 69 different points with the Hylleraas-configuration interaction method using 13s3pld Cartesian Gaussian basis functions. This new surface is found to be substantially lower in absolute energy than all previous surface calculations. The equilibrium energy of the H3+ molecule has also been calculated with a larger 13s5p3d basis set. The minimum energy was found to be E = -1.343 827 9 hartrees at an internuclear distance of R = 1.6500 bohrs in the equilateral triangle configuration. This energy is significantly ( > 70 cm -I) lower than the previous best published variational calculation and is outside and below the error bars of the latest quantum Monte Carlo calculation. In addition, a medium-sized basis set of 13s4p2d orbitals was used to predict that the equilibrium separation is R = 1.6499 bohrs.

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“…The results obtained with a series of gases were reported and it was also shown that negatively charged canal rays could be formed. In a fourth publication Thomson described what could be called the first mass spectrometer (Thomson, 1912). Rays were deflected by a constant electric field and then by a magnetic field which was increased step by step in small increments.…”

Section: Cathode Rays and Canal Raysmentioning

confidence: 99%

Mass spectrometry and isotopes: A century of research and discussion

Budzikiewicz

Grigsby²

2005

Mass Spectrometry Reviews

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In 1815, the British physician William Prout had advanced the theory that the molecular masses of elements were multiples of the mass of hydrogen. This "whole number rule" (and especially deviations from it) played an important role in the discussion whether elements could be mixtures of isotopes. F. Soddy's discovery (1910) that lead obtained by decay of uranium and of thorium differed in mass was considered a peculiarity of radioactive materials. The question of the existence of isotopes came up when the instruments developed by J.J. Thomson and by W. Wien to study cathode and canal rays by deflection in electric and magnetic fields were steadily improved. In 1913, Thomson mentioned a weak line at mass 22 accompanying the expected one at mass 20 when he analyzed the mass spectrum of neon. Subsequently Aston obtained the mass spectrum of chlorine with masses at 35 and 37. Still in 1921, Thomson objected heavily to the idea of isotopes. The isotope problem was finally settled, but more accurate mass measurements showed that even isotopic weights differed to some extent from the whole numbers. Based on earlier ideas of P. Langevin and J.-L. Costa, F.W. Aston and A.J. Dempster developed the idea of packing fractions and mass defects due to the transformation of a portion of the matter comprising the atomic nucleus into energy. While the determination of the exact isotopic masses had improved over the years, the accurate determination of isotopic abundances remained a problem as long as photographic recording was used. Here especially A.O. Nier pioneered using dual collectors and compensation measurements. This was the prerequisite for the discovery that isotopic ratios varied somewhat in nature. M. Dole discovered the fractionation of oxygen isotopes by photosynthesis and respiration. Today 13C/12C-ratios are employed to detect adulterations of food and in doping analysis, and 14C/13C-ratios obtained by accelerator mass spectrometry are used for dating historical objects, just to give some examples.

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XIX. Further experiments on positive rays

Cited by 153 publications

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Visible transitions from ground state H ₃ ⁺ measured with high-sensitivity action spectroscopy

Visible transitions from ground state H ₃ ⁺ measured with high-sensitivity action spectroscopy

Gaussian functions in Hylleraas-configuration interaction calculations. V. An accurate a b i n i t i o H+3 potential-energy surface

Mass spectrometry and isotopes: A century of research and discussion

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XIX. Further experiments on positive rays

Cited by 153 publications

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Visible transitions from ground state H 3 + measured with high-sensitivity action spectroscopy

Visible transitions from ground state H 3 + measured with high-sensitivity action spectroscopy

Gaussian functions in Hylleraas-configuration interaction calculations. V. An accurate a b i n i t i o H+3 potential-energy surface

Mass spectrometry and isotopes: A century of research and discussion

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Visible transitions from ground state H ₃ ⁺ measured with high-sensitivity action spectroscopy

Visible transitions from ground state H ₃ ⁺ measured with high-sensitivity action spectroscopy