An NMR Investigation of Internal Molecular Motion in Liquid Ethanol

Ansari, Muhammad Shahid; Hertz, H. G.

doi:10.1524/zpch.1983.137.2.187

Cited by 14 publications

(24 citation statements)

References 29 publications

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“…(1) at the outset are considered to be unknown weight factors we have chosen the symbol wj. This is in a certain contrast to our previous paper [4] where in Eqs. (5) and (6) the coefficients of the exponentials were called a} and a] and where these coefficients were understood as being functions of the angles derived from molecular geometry.…”

Section: Introductioncontrasting

confidence: 97%

“…1 shows 1/7*1. f°r the methyl protons as a function of 1000/F. This is the total relaxation rate, the results are in satisfactory agreement with the corresponding relaxation rates reported previously [4]. In that work, also the intramolecular relaxation rate has been determined.…”

supporting

confidence: 90%

“…A second resistance thermometer measured the temperature at the top of the sample. These resistance thermometers were calibrated against a certified Pt-resistence thermometer to yield temperature more accurate than ±0.1 K [4]. The temperature gradient over the sample volume was ± 1 K at maximum and the total uncertainty was estimated to be ± 1.5 K. The resulting total uncertainty in 7j is estimated to be 5 -10%.…”

Section: Methodsmentioning

confidence: 99%

“…Furthermore, for the CH2 and CH3 groups under varying conditions certain relations between the various as required by the theory could not be verified [3,7], and finally there do already exist experimental investigations which did not reveal the multi-term structure of Eq. (1) [4,[16][17][18], Now the fundamental problem with which we are confronted is to get information about a kind of molecular motion the time constants of which are two to three orders of magnitude shorter than the observation time inherent in the method used, which is the reciprocal nuclear magnetic resonance frequency, co~l. This means that we have coxc<^\, or atteff<^l, a situation which is called the extreme narrowing behaviour.…”

Section: Introductionmentioning

confidence: 99%

“…(7) increases, then passes through a maximum, and finally becomes vanishingly small [7], So, if the t°a nd the corresponding activation energies in Eq. (9) are sufficiently different we expect a series of maxima to appear as we lower the temperature, one following the other [7], The maxima may partly be unresolved, then the total experimental curve l/7\(l/7/) has to be decomposed suitably to yield the various contributions Wjf(Xj,cCnj) [4], The function f(tj,a)Xj) as given in Eq. (7) has its maximum when t/o = 0.62, substitution of this result in Eq.…”

Section: Introductionmentioning

confidence: 99%

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Internal Motion in Liquid Ethanol and some Other Alcohols, Separation of Contributions by Added Glycerol

Hertz¹,

Wild²,

Weingärtner³

1984

Zeitschrift Für Physikalische Chemie

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Liquids I Internal rotation I Nuclear magnetic relaxation 'H nuclear magnetic relaxation rates of CH3CD2OD and CD3CH2OD in various mixtures with glycerol-d8 in the temperature range 120< T<300K have been measured. Whereas the log(1/rl)(l/D curve for pure ethanol shows only the simple "elementary form" with one maximum, in agreement with Versmold's observation on the deuteron relaxation the addition of glycerol produces shoulders or second maxima. For comparison i-propanol (CH3)2CDOD and CH3OD were also studied in their mixtures with glycerol-d8. In the former case a shoulder appeared on the log(l/7",)(l/7*) curve, in the latter case no particularities showed up. It turned out that the weight factors derived from these observations could not be correlated with conventional molecular geometry in a satisfactory way. Die kernmagnetischen 'H-Relaxationsraten von CH3CD2OD und CD3CH2OD in verschiedenen Gemischen mit Glycerin-d8 wurden in einem Temperaturbereich von 120 bis 300 K gemessen. Wahrend die log(l/T1)(l/T)-Kurve fur reincs Athanol nur die einfache ..Elementarform" mit einem Maximum zeigt, bewirkt in Ubereinstimmung mit Versmolds Befunden an der Deuteronenrelaxation die Beimischung von Glycerin das Auftreten von Schultern oder zweiten Maxima. Zum Vergleich wurden auch i-Propanol (CH3)2CDOD und CH3OD in ihren Gemischen mit Glycerin-d8 untersucht. Im ersteren Falle erschien gleichfalls eine Schulter an der log(1/7,1)(l/r)-Kurve, im letzteren Falle traten keine Besonderheiten auf. Eszeigtesich, daBdie Gewichtsfaktoren, die aus diesen Messungen erhalten wurden, sich nicht in befriedigender Weise mit den Parametern der iiblich anerkannten Molekiilgeometrie verkniipfen lassen.

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Section: Introductioncontrasting

confidence: 97%

supporting

confidence: 90%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Internal Motion in Liquid Ethanol and some Other Alcohols, Separation of Contributions by Added Glycerol

Hertz¹,

Wild²,

Weingärtner³

1984

Zeitschrift Für Physikalische Chemie

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Rotational, Internal Rotational, and Translational Motion of Liquid i‐Propanol

Frech

Hertz

1985

Ber Bunsenges Phys Chem

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Deuteron magnetic relaxation rates of the following isotopically substituted i-propanols (CH,),CHOD, (CH,),CDOH, and (CD,),CHOH have been measured as a function of the temperature and the frequency. Thus the present investigations were performed in the dispersion range. We have attempted to interpret these relaxation rates within the framework of the Woessner theory of internal rotation. The success was not satisfactory, the quadrupole coupling constants were smaller than expected. Proton magnetic relaxation rates of the two i-propanols (CD,),CDOH and (CH,),CDOD have also been measured as a function of the temperature and the frequency. Separation of intra-and intermolecular contributions was performed by usual isotopic dilution technique. With the intramolecular relaxation rates again difficulties to describe internal rotation appeared. The dipole-dipole coupling constant came out too small. The intermolecular relaxation rates could be related to intermolecular configurations fairly satisfactory, although dynamical descriptions still leaves open questions.

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Investigation of Complex Intramolecular Motion in Supercooled Liquids

Pösch

Althoff

Killie

et al. 1991

Ber Bunsenges Phys Chem

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After a brief résumé of the Woessner theory which treats nuclear magnetic relaxation effects caused by internal and anisotropic motion of molecules in liquids we present proton magnetic relaxation rates of specifically deuterated molecules possessing an interacting group (–OH or –COOH) and a hydrocarbon chain of increasing length, namely methanol and acetic acid, ethanol and propionic acid, n‐propanol. Measurements were done in the range from room temperature to ∼ 15 K. Various interacting substances were added to slow down the movement of the interacting group relative to the internal molecular motions, yielding respective experimental manifestations. Some brief hints are given to show the shortcomings of the Woessner theory.

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An NMR Investigation of Internal Molecular Motion in Liquid Ethanol

Cited by 14 publications

References 29 publications

Internal Motion in Liquid Ethanol and some Other Alcohols, Separation of Contributions by Added Glycerol

Internal Motion in Liquid Ethanol and some Other Alcohols, Separation of Contributions by Added Glycerol

Rotational, Internal Rotational, and Translational Motion of Liquid i‐Propanol

Investigation of Complex Intramolecular Motion in Supercooled Liquids

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