Observation of high vibrational excitation in HCN molecules produced from 193 nm photolysis of 1,3,5-triazine

Goates, Steven R.; Chu, J. O.; Flynn, George W.

doi:10.1063/1.447422

Cited by 27 publications

(41 citation statements)

References 18 publications

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“…This last mechanism is supported by the computational studies of Politzer and coworkers [8] as well as the classical dynamics calculations of Sewell and Thompson [9]. There is experimental and theoretical evidence that the aromatics 1,3,5-triazine (s-triazine) [10][11][12][13][14][15][16] and s-tetrazine [17][18][19][20] also undergo three-body unimolecular decomposition when they are highly vibrationally excited on the ground electronic surface, as they are in a thermal reaction. However, the dissociation of the infamous substituted triazine, melamine, 2,4,6-triamino-1,3,5-triazine, evidently follows a radical path [21].…”

Section: Introductionmentioning

confidence: 84%

“…9, but our recent study of HCN itself [48] showed no indication of isomerization, so this seems quite unlikely. Perhaps the HCN is somehow formed with close to equilibrium HNC [11].…”

Section: Dissociationmentioning

confidence: 99%

“…The three-body dissociation of s-triazine (1) is believed to be the dominant channel [10][11][12][13][14][15][16],…”

Section: Introductionmentioning

confidence: 99%

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Shock tube study of 1,3,5‐triazine dissociation and relaxation and relaxation of pyrazine

Kiefer

2010

Int J of Chemical Kinetics

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The three-body dissociation of 1,3,5-triazine (s-triazine, s-C 3 H 3 N 3 → 3HCN) has been observed in incident shock waves with the laser-schlieren technique. The experiments use 5% triazine/Kr and cover 1630-2350 K for 100-600 Torr. These experiments show dissociation rates with strong falloff and a slight but fully expected pressure dependence. The dissociation is without secondary reaction save for a possible, but rather unlikely, contribution from the isomerization HCN → HNC. Electronic structure calculations of the transitionstate properties (G3B3, HL1, E o = 84.6 kcal/mol) are used to construct a Rice-RamspergerKassel-Marcus (RRKM) model whose fit to the rate measurements suggests a E down of 1200 cm −1 . However, a seemingly better fit is achieved using the barrier of 81 kcal/mol proposed by Dyakov et al. (J. Phys. Chem. A 2007, 111, 9591-9599). With this barrier k ∞ (s −1 ) = 5.3 × 10 16 exp(−86.6(kcal/mol)/RT), and the fit now accepts the more routine E down = 126(T /298) 0.9 . It seems the dissociation most likely occurs by a direct, one-step, "triple" dissociation to 3HCN, although the present experiments cannot rule out a multistep process. Vibrational relaxation of the triazine was also examined in 5% and 20% mixtures with Kr over 770-1500 K for pressures between 6 and 14 Torr. Relaxation is very fast, with a slight inverse temperature dependence, P τ rising from 100 to 200 ns-atm over the full temperature range. Integrated gradients are in good accord with calculated total changes in density, indicating a single exponential relaxation. A separate investigation of relaxation in the related molecule pyrazine (500-1300 K, in 1% and 5% in Kr, between 13 and 66 Torr) is included. Again relaxation is rapid, but here the temperature dependence seems more normal, the relaxation times decreasing slightly with temperature. C

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Section: Introductionmentioning

confidence: 84%

“…9, but our recent study of HCN itself [48] showed no indication of isomerization, so this seems quite unlikely. Perhaps the HCN is somehow formed with close to equilibrium HNC [11].…”

Section: Dissociationmentioning

confidence: 99%

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Shock tube study of 1,3,5‐triazine dissociation and relaxation and relaxation of pyrazine

Kiefer

2010

Int J of Chemical Kinetics

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“…More recently, the molecular structure of 1,3,5-triazine ( 12 r(CÀH) 108.9(2) pm, and <(CNC) 113.82 (9) [415]. The photodissociation of symtriazine has been widely studied [416][417][418][419][420][421][422][423][424]. A computational study of the stability, homodesmotic stabilization energy, electron distribution and magnetic ring current of 1,3,5-triazines has been described [53].…”

Section: 41mentioning

confidence: 99%

Six‐Membered Heterocycles: Triazines, Tetrazines and Other Polyaza Systems

Oliva¹,

Laza²,

Ocáriz³

2011

Modern Heterocyclic Chemistry

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“…[43][44][45][46][47][48][49] Sym-triazine is just one of a handful of molecular species known to undergo multibody dissociation. [43][44][45][46][47][48][49] Sym-triazine is just one of a handful of molecular species known to undergo multibody dissociation.…”

Section: B Photodissociation Of Sym-triazine and The Coherent Transimentioning

confidence: 99%

Photodissociation dynamics in “hyper-rovibronic” detail: Exploring the potential of millimeter/submillimeter-wave spectroscopy in molecular reaction dynamics experiments

Duffy

2005

Review of Scientific Instruments

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Articles you may be interested inRotational spectra of rare isotopic species of fluoroiodomethane: Determination of the equilibrium structure from rotational spectroscopy and quantum-chemical calculations Molecules in high spin states III: The millimeter/submillimeter-wave spectrum of the MnCl radical (X 7 Σ + )Over the years, many techniques for studying molecular reaction dynamics have been developed and fine-tuned to probe chemical dynamics at an ever-increasing level of detail. Unfortunately, this progress has frequently come at the price of high experimental cost and great complexity. In this regard experiments employing direct absorption have a distinct advantage in that they are comparatively simple in setup and they probe nascent product distributions directly. Even though the low product number densities in molecular-beam experiments put severe constraints on the noise and sensitivity requirements of detectors, Nesbitt and co-workers ͓J. Chem. Phys. 86, 3151 ͑1987͒; Rev. Sci. Instrum. 58, 807 ͑1987͒; J. Chem. Phys. 85, 4890 ͑1986͒; J. Chem. Phys. 107, 5661 ͑1997͒; Chem. Phys. Lett. 258, 207 ͑1996͔͒ have demonstrated the use of direct infrared absorption in a variety of molecular reaction dynamics studies. In analogous experiments, this article explores the use of millimeter-and submillimeter-wavelength radiation in direct absorption experiments in a molecular beam. The comparatively simple and inexpensive setup demonstrates the utility of combining new commercial solid-state millimeter/submillimeter-wavelength sources with hot-electron bolometer detectors to directly probe parent and product hyperfine rovibronic levels and their Doppler-resolved velocity distributions in a molecular beam. For example, in open-shell products with nuclear spin, the ultrahigh energy resolution of the rotational spectroscopy easily resolves nuclear quadrupole hyperfine structure and lambda doublets in both ground and excited spin-orbit states as well as in ground and excited vibrational levels. Two molecular beam examples are given: ͑1͒ detection of "hyper-rovibronic" structure in ClO ͑ 2 ⌸ ⍀=3/2,1/2 , = 0-8, J =1 1 2 -7 1 2 , ⌳ , F͒ following the mode-specific photodissociation of OClO ͑A 2 A 2 ← X 2 B 1 , 1 = 14-15͒, and ͑2͒ coherent transient absorption of HCN following the 266 nm photodissociation of sym-triazine/argon clusters.

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Observation of high vibrational excitation in HCN molecules produced from 193 nm photolysis of 1,3,5-triazine

Cited by 27 publications

References 18 publications

Shock tube study of 1,3,5‐triazine dissociation and relaxation and relaxation of pyrazine

Shock tube study of 1,3,5‐triazine dissociation and relaxation and relaxation of pyrazine

Six‐Membered Heterocycles: Triazines, Tetrazines and Other Polyaza Systems

Photodissociation dynamics in “hyper-rovibronic” detail: Exploring the potential of millimeter/submillimeter-wave spectroscopy in molecular reaction dynamics experiments

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