Electronic Energy Levels of Small Polyatomic Transient Molecules

Jacox, Marilyn E.

doi:10.1063/1.555822

Cited by 159 publications

(111 citation statements)

References 2 publications

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“…Instead of solidifying below 2.2 K it undergoes a unique phase transition to a superfluid state called HeII. The transition temperature for the bosonic (nuclear spin I = 0) 4 He isotope is T = 2.18 K. The fermionic (I = 1 = 2 ) 3 He isotope becomes superfluid at a much lower temperature, T = 3 10 À3 K (which is not relevant for the present Review). Superfluid 4 He exhibits a range of unusual phenomena, such as a vanishingly small viscosity, a very high heat conductivity (30-times greater than copper) and many other bizarre effects, such as the He fountain, film flow and creep, and quantized vortices.…”

Section: Comparison Of Seeded Molecular Beams and Other Cryomatrices mentioning

confidence: 88%

“…The large increases in both L* and V 0 /R À1 0 in going from the heavy rare gases to H 2 , 4 He, and 3 He are thus attributed to an increase in the zero-point energy and the resulting increase in the delocalization of the matrix particles. In the case of helium this quantum effect is largest and explains why it is the only substance, which remains liquid at saturated vapor pressures even down to absolute zero.…”

Section: Comparison Of Seeded Molecular Beams and Other Cryomatrices mentioning

confidence: 98%

“…From the 4 He phase diagram another unique property is apparent. Instead of solidifying below 2.2 K it undergoes a unique phase transition to a superfluid state called HeII.…”

Section: Comparison Of Seeded Molecular Beams and Other Cryomatrices mentioning

confidence: 99%

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Superfluid Helium Droplets: A Uniquely Cold Nanomatrix for Molecules and Molecular Complexes

2004

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Herein, recent experiments on the spectroscopy and chemical reactions of molecules and complexes embedded in helium droplets are reviewed. In the droplets, a high spectroscopic resolution, which is comparable to the gas phase is achieved, while an isothermal low-temperature environment is maintained by evaporative cooling at T =0.37 K (4He droplets) or 0.15 K (3He droplets), lower than possible in most solid matrices. Thus the helium-droplet technique combines the benefits of both the gas phase and the classical matrix-isolation techniques. Most important, the superfluid helium facilitates binary encounters, and absorbs the released binding energy upon recombination. Thus the droplet can be viewed as an isothermal nanoscopic reactor, which isolates single molecules, clusters, or even a single reactive encounter at ultralow temperatures.

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Section: Comparison Of Seeded Molecular Beams and Other Cryomatrices mentioning

confidence: 88%

Section: Comparison Of Seeded Molecular Beams and Other Cryomatrices mentioning

confidence: 98%

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Superfluid Helium Droplets: A Uniquely Cold Nanomatrix for Molecules and Molecular Complexes

2004

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“…The obtained experimental apparent activation energies of reaction @a), (318210) W mol-', and reaction (6), (313215) W mol-', were used to calculate the dissociation energy of NH and NH2. At a mean temperature of 2850 K and by using the vibrational frequencies and rotational constants given in [43] Eq. =(196k13) kJ mol-' were obtained in a previous study of our group [4] of the unimolecular decomposition of NH3.…”

Section: Discussionmentioning

confidence: 99%

The Thermal Decomposition of NH₂ and NH Radicals

Deppe

Friedrichs

Ibrahim

et al. 1998

Ber Bunsenges Phys Chem

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The formation of NH2 and NH radicals as well as H and N atoms during the thermal decomposition of hydrazine was investigated over a wide temperature range. For the first time frequency-modulated spectroscopy was used for the detection of NHp radicals behind shock waves. In comparison with the dual beam laser absorption technique, the detection limit has been improved by one and a half orders of magnitude.For reaction (5a) NH2+M + NH+H+M the rate constants were obtained in the temperature range from 2200 to 4000 K ks,=(1.2+0.5)10's~exp [-(318* 10) kJ mol-'/RT] cm'lmol s and for reaction (6) N H c M --t N + H + M in the temperature range from 2500 to 3400 K k6=(l.8+0.8)10'4.exp [-(313? 15) kJ mol-'/RT] cm3/mol s.The experimental apparent activation energies were found to be in good agreement with theoretical calculations and recently recommended enthalpies of formation for NH2 and NH. The competing NH2 decomposition channel (5b) NHz+M -+ N+H2+M was shown to be of minor importance ( < 5%). The kinetic behavior of the unimolecular decomposition of NH2 is compared with that of H20 and k H 2 .

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“…The energy difference between the 0 0 0 and 4 0 1 bands in the gas phase is 1916 cm Ϫ1 . Though the absolute neon-gas shifts are large, it is known that the vibrational frequencies generally lie within a few cm Ϫ1 [13]. The second set of measurements involved using deutero-acetylene in the discharge.…”

Section: Observationsmentioning

confidence: 99%

Electronic spectra of C₆H⁺ and C₆H₃⁺ in the gas phase

Raghunandan

Mazzotti

Maier

2010

J. Am. Soc. Mass Spectrom.

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Measurement of the 3 ⌸ Ϫ 3 ⌸ transition of C 6 H ϩ in the gas phase near 19486 cm Ϫ1 is reported. The experiment was carried out with a supersonic slit-jet expansion discharge using cavity ringdown absorption spectroscopy. Partly resolved P lines and observation of band heads permitted a rotational contour fit. Spectroscopic constants in the ground and excited-state were determined. The density of ions being sampled is merely 2 ϫ 10 8 cm Ϫ3 . Broadening of the spectral lines indicates the excited-state lifetime to be Ϸ100 ps. The electronic transition of HC 6 H 2 ϩ at 26402 cm Ϫ1 assumed to be 1 A 1 Ϫ X 1 A 1 in C 2v symmetry could not be rotationally resolved. (J Am Soc Mass Spectrom 2010, 21, 694 -697)

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Electronic Energy Levels of Small Polyatomic Transient Molecules

Cited by 159 publications

References 2 publications

Superfluid Helium Droplets: A Uniquely Cold Nanomatrix for Molecules and Molecular Complexes

Superfluid Helium Droplets: A Uniquely Cold Nanomatrix for Molecules and Molecular Complexes

The Thermal Decomposition of NH₂ and NH Radicals

Electronic spectra of C₆H⁺ and C₆H₃⁺ in the gas phase

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Electronic Energy Levels of Small Polyatomic Transient Molecules

Cited by 159 publications

References 2 publications

Superfluid Helium Droplets: A Uniquely Cold Nanomatrix for Molecules and Molecular Complexes

Superfluid Helium Droplets: A Uniquely Cold Nanomatrix for Molecules and Molecular Complexes

The Thermal Decomposition of NH2 and NH Radicals

Electronic spectra of C6H+ and C6H3+ in the gas phase

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The Thermal Decomposition of NH₂ and NH Radicals

Electronic spectra of C₆H⁺ and C₆H₃⁺ in the gas phase