Vacuum-ultraviolet photolysis of methylamine

Gardner, Edward P.; McNesby, J. R.

doi:10.1021/j100211a019

Cited by 35 publications

(19 citation statements)

References 11 publications

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“…The behavior of the studied molecules resembles their UV photochemistry: Gas‐phase photolysis of methylamine at 184.9 nm yields, with unity quantum yield, the radical CH 3 NH* which subsequently decomposes by loss of another H atom to the imine CH 2 NH. At higher photon energies direct elimination of H 2 from methylamine gains importance . The methylamidogen radical can also be detected by ESR spectroscopy during photolysis of the pure amine at 77 K .…”

Section: Are Amino Groups Stable At All Under Exposure To Plasma Condmentioning

confidence: 99%

“…At higher photon energies direct elimination of H 2 from methylamine gains importance. [55] The methylamidogen radical can also be detected by ESR spectroscopy during photolysis of the pure amine at 77 K. [56] Imines are also formed by vapor-phase photolysis of higher primary amines such as butylamine (Bu─NH 2 ), following the N─H dissociation: 2 Bu─NH* → Bu─NCH─Pro + NH 3 (Pro = propyl). [57] n-Hexylamine (Hex─NH 2 ) dissolved in cyclohexane provides, upon irradiation from a medium-pressure Hg arc lamp, the corresponding imine, Hex─NCH─Pen (Pen = pentyl) as the major product.…”

Section: All Under Exposure To Plasma Conditions?mentioning

confidence: 99%

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Critical remarks on chemical derivatization analysis of plasma‐treated polymer surfaces and plasma polymers

Klages

Kotula

2016

Plasma Processes & Polymers

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The notion that individual functional groups on plasma‐modified polymer surfaces or in plasma polymers can be detected and quantified using selectively reacting derivatization reagents has dominated the field of plasma‐based surface technology since more than 30 years. For nitrogenated films and surfaces it has traditionally been believed that amino groups can be analyzed selectively using electrophilic reagents such as benzaldehydes or carboxylic acid anhydrides. This article presents arguments indicating that traditionally applied methodologies are partially based on myths. Presumed amino groups are – at least to a substantial extent – probably in fact other nitrogen‐bearing moieties. It is open to question if primary or secondary amino groups could “survive” the physico‐chemical environment typical of a plasma at all. Advancing the chemical understanding of N‐containing plasma‐generated films and surfaces, and plasma‐chemical formation mechanisms requires rethinking the interpretation of derivatization experiments.

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Section: Are Amino Groups Stable At All Under Exposure To Plasma Condmentioning

confidence: 99%

Section: All Under Exposure To Plasma Conditions?mentioning

confidence: 99%

Critical remarks on chemical derivatization analysis of plasma‐treated polymer surfaces and plasma polymers

Klages

Kotula

2016

Plasma Processes & Polymers

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“…As the solute size increases (to ≈ 1 nm at ambient conditions) [42,43,44,45], such clathrate-like structure cannot be maintained: HBs break, inducing a restruc-turing of the HB network. In this case, the hydration structure shows an orientational inversion with respect to the clathrate-like structure, with HBs pointing toward the solute [42,43,46,47,48]. When two hydrophobic surfaces approach each other, a confined water film can be thermodynamically destabilized with respect to the vapor at small enough separations [21,24,35,36,49].…”

Section: Introductionmentioning

confidence: 99%

Effect of pressure on the phase behavior and structure of water confined between nanoscale hydrophobic and hydrophilic plates

2006

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We perform systematic molecular dynamics simulations of water confined between two nanoscale plates at T = 300K. We investigate the effect of pressure (-0.15 GPa< or = P< or =0.2GPa) and plate separation (0.4 nm < or =d < or =1.6 nm) on the phase behavior of water when the plates are either hydrophobic or hydrophilic. When water is confined between hydrophobic plates, capillary evaporation occurs between the plates at low enough P. The threshold value of d at which this transition occurs decreases with P (e.g., 1.6 nm at P approximately equal to -0.05 GPa, 0.5 nm at P approximately equal to 0.1 GPa), until, at high P, no capillary evaporation occurs. For d approximately equal to 0.6 nm and P > or =0.1 GPa, the system crystallizes into a bilayer ice. A P-d phase diagram showing the vapor, liquid, and bilayer ice phases is proposed. When water is confined by hydrophilic (hydroxylated silica) plates, it remains in the liquid phase at all P and d studied. Interestingly, we observe for this case that even at the P at which bulk water cavitates, the confined water remains in the liquid state. We also study systematically the state of hydration at different P for both kinds of plates. For the range of conditions studied here, we find that in the presence of hydrophobic plates the effect of P is to enhance water structure and to push water molecules toward the plates. The average orientation of water molecules next to the hydrophobic plates does not change upon pressurization. In contrast, in the presence of hydrophilic plates, water structure is insensitive to P. Hence, our results suggest that upon pressurization, hydrophobic plates behave as "soft" surfaces (in the sense of accommodating pressure-dependent changes in water structure) while hydrophilic walls behave as "hard" surfaces.

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“…A cross section was constructed from the photoabsorption measurements of Hubin-Franskin et al (2002) (138 to 249 nm), combined with their simultaneously-recorded electron-energy-loss-derived cross section (83 to 138 nm) and another lower-resolution electron-energy loss measurement (Burton et al 1994) shorter than 83 nm. Some information on branching ratios to various products is available at a few wavelengths (Michael & Noyes 1963;Gardner & McNesby 1982).…”

Section: Ch 3 Nh 2 -Methylaminementioning

confidence: 99%

Photodissociation and photoionisation of atoms and molecules of astrophysical interest

Heays

Bosman

Dishoeck

2017

A&A

443

442

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A new collection of photodissociation and photoionisation cross sections for 102 atoms and molecules of astrochemical interest has been assembled, along with a brief review of the basic physical processes involved. These have been used to calculate dissociation and ionisation rates, with uncertainties, in a standard ultraviolet interstellar radiation field (ISRF) and for other wavelength-dependent radiation fields, including cool stellar and solar radiation, Lyman-α dominated radiation, and a cosmic-ray induced ultraviolet flux. The new ISRF rates generally agree within 30% with our previous compilations, with a few notable exceptions. Comparison with other databases such as PHIDRATES is made. The reduction of rates in shielded regions was calculated as a function of dust, molecular and atomic hydrogen, atomic C, and self-shielding column densities. The relative importance of these shielding types depends on the atom or molecule in question and the assumed dust optical properties. All of the new data are publicly available from the Leiden photodissociation and ionisation database. Sensitivity of the calculated rates to variation of temperature and isotope, and uncertainties in measured or calculated cross sections, are tested and discussed. Tests were conducted on the new rates with an interstellar-cloud chemical model, and find general agreement (within a factor of two) in abundances obtained with the previous iteration of the Leiden database assuming an ISRF, and order-of-magnitude variations assuming various kinds of stellar radiation. The newly parameterised dust-shielding factors makes a factor-of-two difference to many atomic and molecular abundances relative to parameters currently in the UDfA and KIDA astrochemical reaction databases. The newly-calculated cosmic-ray induced photodissociation and ionisation rates differ from current standard values up to a factor of 5. Under high temperature and cosmic-ray-flux conditions the new rates alter the equilibrium abundances of abundant dark cloud abundances by up to a factor of two. The partial cross sections for H 2 O and NH 3 photodissociation forming OH, O, NH 2 and NH are also evaluated and lead to radiation-field-dependent branching ratios.

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Vacuum-ultraviolet photolysis of methylamine

Cited by 35 publications

References 11 publications

Critical remarks on chemical derivatization analysis of plasma‐treated polymer surfaces and plasma polymers

Critical remarks on chemical derivatization analysis of plasma‐treated polymer surfaces and plasma polymers

Effect of pressure on the phase behavior and structure of water confined between nanoscale hydrophobic and hydrophilic plates

Photodissociation and photoionisation of atoms and molecules of astrophysical interest

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