Raman spectra and phase transition of crystalline CH3CN and CD3CN

Marzocchi, Mario P.; Migliorini, Maria Grazia

doi:10.1016/0584-8539(73)80114-x

Cited by 24 publications

(14 citation statements)

References 5 publications

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“… a Assignments from published report for pure acetonitrile b Pure orthorhombic CH 3 CN spectrum collected at 200 K. c Orthorhombic CH 3 CN at 80 K (Form II), after annealing at 210 K for 1 h d Pure monoclinic CH 3 CN spectrum collected at 90 K (phase-trapped). e Monoclinic CH 3 CN at 80 K (Form I), formed via vapor deposition (phase-trapped) and annealed at 120 K …”

Section: Resultsmentioning

confidence: 99%

Properties and Behavior of the Acetonitrile–Acetylene Co-Crystal under Titan Surface Conditions

Cable

Malaska

et al. 2020

ACS Earth Space Chem.

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Titan, the largest satellite of Saturn, possesses a complex photochemical cycle producing a broad inventory of organic molecules in its thick atmosphere and on its surface. Two of the most common molecules in this inventory include acetylene (C2H2) and acetonitrile (CH3CN). We have previously demonstrated that certain organic molecules (such as benzene and ethane) readily form co-crystals under Titan-relevant conditions. Here, we report Raman spectroscopic and X-ray diffraction evidence for a co-crystal between acetonitrile and acetylene at Titan surface conditions. This molecular mineral could be relatively abundant on Titan, in particular in the large fluvially dissected plateaux of labyrinth terrains and possibly the undifferentiated plains, which are believed to be the end-stage product of the labyrinth terrains. Co-crystals might provide a mechanism for storing energy-rich molecules such as acetylene, permitting sequestration and transport to the subsurface where these deposits could be accessed by putative life.

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Section: Resultsmentioning

confidence: 99%

Properties and Behavior of the Acetonitrile–Acetylene Co-Crystal under Titan Surface Conditions

Cable

Malaska

et al. 2020

ACS Earth Space Chem.

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“…Calorimetric measurements 17 have shown that bulk acetonitrile undergoes a solid II ! solid I phase transition at 217-218 K and melts at 228-229 K. IR and Raman investigations [18][19][20] have confirmed the existence of the two solid phases. Barrow 21 had established already in 1981, in an X-ray study, that the high-temperature crystal phase of acetonitrile, solid I, is monoclinic at 215 K. Later, Torrie and Powell 22 determined the structure of the low-temperature phase of acetonitrile-d 3 , solid II, to be orthorhombic at 12 K, using neutron powder…”

Section: Introductionmentioning

confidence: 80%

Dynamic¹H and²H NMR investigations of acetonitrile confined in porous silica

Aksnes

Gjerdåker

Kimtys

et al. 2003

Phys. Chem. Chem. Phys.

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In this work, the molecular dynamics of acetonitrile and acetonitrile-d 3 confined in silica pores of nominal diameter 6 and 20 nm are studied by high field 1 H and 2 H NMR, and the results are discussed with reference to the bulk substances. NMR line-shapes, spin-lattice relaxation times (T 1 ), spin-spin relaxation times (T 2 ) and diffusivities (D) are reported as a function of temperature. The line-shape and relaxation measurements clearly reveal a two-component system in the solid phase, consisting of a narrow line superimposed on a broad complex resonance. The melting process takes place over a certain temperature region, due to an appreciable pore size distribution. Below the melting region, the narrow line originates solely from the surface layer, while the broad line is attributed to the crystalline solid at the interior of the pore. The confining geometry restricts the mobility of the liquid probe molecules and gives rise to significantly shorter T 1 and T 2 relaxation times and reduced self-diffusion rates, as compared to the bulk substance. This observation is also reflected in increased activation energies of the reorientational and translational motions. True intragrain diffusivities were obtained for the probe molecules by using the short diffusion time model, and extrapolating to zero observation time.

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“…This discrepancy between the ideal and actual packing arrangements most likely results from the anisotropic intermolecular interactions which exist in the acetonitrile crystal. Information on the arrangement of the molecules in/3-acetonitrile has been obtained previously from an investigation of the nuclear quadrupole resonance spectrum (Casabella & Bray, 1958) and from Raman and infrared spectroscopy (Milligan & Jacox, 1962;Pace & Noe, 1968;Marzocchi & Migliorini, 1973). These studies show that the molecules are in nearly axial alignment in the crystal.…”

Section: Discussion and Concluding Remarksmentioning

confidence: 99%