New Knudsen effusion apparatus with simultaneous gravimetric and quartz crystal microbalance mass loss detection

Santos, Luı́s M. N. B. F.; Lima, Luís M. Spencer S.; Lima, Carlos F. R. A. C.; Magalhães, Fernão D.; Torres, Manuel C.; Schröder, Bernd; Silva, Manuel A.V. Ribeiro da

doi:10.1016/j.jct.2010.12.022

Cited by 69 publications

(44 citation statements)

References 32 publications

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“…31,33,40 The standard molar Gibbs energies of sublimation were calculated through eq 8 where the parameters are referenced to T = 298.15 K. Table 8 lists the derived standard molar enthalpies, entropies, and Gibbs energies of sublimation, at T = 298.15 K, for the compounds studied.…”

Section: Vapor Pressures and Thermodynamic Properties Of Sublimation mentioning

confidence: 99%

Description and Test of a New Multilayer Thin Film Vapor Deposition Apparatus for Organic Semiconductor Materials

et al. 2015

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In this work the description, test, and performance of a new vacuum apparatus for thin film vapor deposition (ThinFilmVD) of organic semiconductor materials are presented. The apparatus is able to fabricate single, multilayer/composites, or hybrid thin films using four independent, organic or inorganic, vapor deposition sources (Knudsen cells type), and the vapor mass flow is condensed onto a substrate surface (temperature regulated). The same apparatus could be also used to measure vapor pressures according to the Knudsen effusion methodology. Vapor pressures and thermodynamic properties of sublimation measured by Knudsen effusion of some reference organic materials (benzoic acid, anthracene, triphenylene, benzanthrone, 1,3,5-triphenylbenzene, perylene) were used to evaluate and test the performance of the apparatus. Moreover, nanostructures of thin films and composite materials of relevant charge transport and electroluminescent materials were deposited onto an indium−tin oxide (ITO) surface, and the morphology and thin film thickness were evaluated by scanning electron microscopy (SEM), exploring the effect of different mass flow rates and deposition time. The new physical vapor deposition apparatus based in four Knudsen effusion cells with an accurate mass flow control was designed to assemble well-defined (composition, morphology, thickness) thin films of organic semiconductors based on their volatility. The described apparatus presents a high versatility to the fabrication of single/multilayer thin films, as-grown crystals, and hybrid micro-and nanostructured materials.

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Section: Vapor Pressures and Thermodynamic Properties Of Sublimation mentioning

confidence: 99%

Description and Test of a New Multilayer Thin Film Vapor Deposition Apparatus for Organic Semiconductor Materials

et al. 2015

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“…The vapor pressures of the studied compounds as a function of temperature were measured by the combined Knudsen/Quartz crystal effusion apparatus recently developed in our laboratory. [49] This technique is based on the simultaneous gravimetric and quartz-crystal microbalance mass-loss detection, enabling the use of a temperature-step methodology, and with the advantages of smaller sample sizes and shorter effusion times, and the possibility of achieving temperatures up to 650 K. In a typical Knudsen effusion experiment the system is kept at high vacuum, enabling free effusion of the vapor from the cell, while the oven is kept at a fixed temperature, T.…”

Section: Knudsen/quartz Crystal Effusionmentioning

confidence: 99%

Experimental Support for the Role of Dispersion Forces in Aromatic Interactions

Lima

Rocha

Gomes

et al. 2012

Chemistry A European J

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Herein a core scaffold of 1-phenylnaphthalenes and 1,8-diphenylnaphthalenes with different substituents on the phenyl rings was used to study substituent effects on parallel-displaced aromatic π⋅⋅⋅π interactions. The energetics of the interaction was evaluated in gas phase based on the standard molar enthalpies of formation, at T=298.15 K, for the compounds studied; these values were derived from the combination of the results obtained by combustion calorimetry and Knudsen/Quartz crystal effusion. A homodesmotic gas-phase reaction scheme was used to quantify and compare the intramolecular interaction enthalpies in various substituted 1,8-diphenylnaphthalenes. The application of this methodology allowed a direct evaluation of aromatic interactions, and showed that substituent effects on the interaction enthalpy cannot be rationalized solely on classical electrostatic grounds, because no correlation with the σ(meta) or σ(para) Hammett constants was observed. Moreover, the results obtained indicate that aromatic π⋅⋅⋅π interactions are significantly enhanced by substitution, in a way that correlates with the ability of the interacting aryl rings to establish dispersive interactions. A combined experimental and computational approach for calculation of the true aromatic π⋅⋅⋅π interaction energies in these systems, free of secondary effects, was employed, and corroborates the rationale derived from the experimental results. These findings clearly emphasize the role of dispersion and dilute the importance of electrostatic forces on this type of interactions.

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“…Then the heat of sublimation can be derived from the dependence of the vapour pressure on the temperature using the Clausius-Clapeyron equation. Examples of indirect techniques are Knudsen's effusion [8][9][10][11] and Langmuir's method [12][13][14][15][16][17][18], which is adopted in this work.…”

Section: Introductionmentioning

confidence: 99%

Enthalpies of sublimation of ferrocene and nickelocene measured by calorimetry and the method of Langmuir

Rojas¹,

Vieyra-Eusebio²

2011

The Journal of Chemical Thermodynamics

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New Knudsen effusion apparatus with simultaneous gravimetric and quartz crystal microbalance mass loss detection

Cited by 69 publications

References 32 publications

Description and Test of a New Multilayer Thin Film Vapor Deposition Apparatus for Organic Semiconductor Materials

Description and Test of a New Multilayer Thin Film Vapor Deposition Apparatus for Organic Semiconductor Materials

Experimental Support for the Role of Dispersion Forces in Aromatic Interactions

Enthalpies of sublimation of ferrocene and nickelocene measured by calorimetry and the method of Langmuir

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