Debye unit of dipole

Second virial coefficient Third virial coefficient Fourth virial coefficient Debye (unit of dipole moment equal to 10 e.s.u.-cm)... 

It was the merit of the theory to have attracted attention to the large variations (2 to 5 Debye units) of dipole moments possibly associated with such tautomerism and to the specific directions of the variation following the nature of the purine. Thus the prediction was that, while the dipole moment of the N(7)H tautomer of purine should be greater than that of its N(9)H tautomer, the dipole moment of the N(7)H tautomer of xanthine should be smaller than... 

Values of the dipole moment of some diatomic molecules are given in Table 2.11. The SI unit of dipole moment is the coulomb-meter (C-m). This is a very large unit, so in Table 2.11 we use the unit 10-30 C-m. Dipole moments are often quoted in an older unit, the debye (D) 1 D = 3.24 X 1CT30 C-m. We can see from Table 2.11 that the dipole moment of a diatomic molecule usually reflects the difference between the electronegativities of the two atoms. 

The unit of Dipole Moment is DEBYE (D) after the name of the researcher. 

Since hv has units of energy, the third term has units J (m3)2 = J m6. The debye is widely used as a unit of dipole moment. It is equal to 10 18 esu cm. To convert this to SI we write... 

Debye = 0.3934267 atomic units of dipole strength = 3.335611x10 30 C m. 

Steady-State Fluorescence. The fluorescence characteristics of PRODAN are extremely sensitive to the physicochemical properties of the solvent (38). As benchmarks, the steady-state emission spectra for PRODAN in several liquid solvents are presented in Figure 1. It is evident that the PRODAN emission spectrum red shifts with increasing solvent polarity. This red shift is a result of the dielectric properties of the surrounding solvent and the large excited-state dipole moment (ca. 20 Debye units) of PRODAN (38). It is the sensitivity of the PRODAN fluorescence that will be used here to investigate the local solvent composition in binary supercritical fluids. 

Equations (4.35) and (4.36) show that the SI unit of dipole moment is the product of the SI units of charge and distance, which are the coulomb and the metre, respectively. However, the unit of C m is a rather cumbersome one, and the old unit of the Debye (D) is still commonly used for the reason that molecular dipole moments are conveniently of the order of 1 D. The units are related by... 

Quantitatively, using the Debye unit, the dipole moments of NH3 (1.47 D), NF3 (0.2 D) and C6H5CH3 (0.36 D) confirm the simple arguments which we have made about their magnitudes. 

The order of magnitude of such a dipole will be equal to the product of the charge on an electron (1.6 x 10 19 C) and a typical bond length (10 10 m) giving a value of 10" 29 Cm. The old electrostatic Debye unit of molecular dipoles was in fact equivalent to 3.335 x 10 30 Cm. Orientation of such molecular dipoles will clearly produce an extra contribution to the molar polarisation in addition to dipoles induced by the applied field, and it is not unreasonable to expect that the equilibrium degree of orientation in a given field will depend on temperature. 

Pyrazine forms an azeotrope with water [60% pyrazine-40% water, b.p. 95.5° (uncorr.) (760mmHg) /ip 1.4510] (578). A method of assay for pyrazine and some common impurities has been developed (579). The dipole moment (Debye units) of pyrazine has been determined in dioxane, cyclohexane, and benzene as zero (580, cf. 581) and it has also been calculated as zero (133, 582). The e.s.r. spectrum (583) and the polarized single-crystal absorption spectra of pyrazine (and tetramethylpyrazine) (584) have been recorded. The photoelectron spectra of pyrazine and tetramethylpyrazine have been determined and suggest a different behavior towards electrophilic attack in the two cases (585). 

In the expressions above, D is the Debye unit of electric dipole moment, and B the Buckingham unit for the electric quadrupole moment. 

Dipole Moments (Debye Units) of 2-SuBsmvrBD Derivatives of Furan, Thiophene, Sblenophene, and Tellurophbne in Benzene... 

Conversion factors for a few other units, which are not related to SI but which are necessary to read the existing literature, are as follows. One atomic unit of length equals 0.52918 Angstroms (A). One atomic unit of dipole moment (two unit charges separated by ao) equals 2.5418 Debyes (D), and one atomic unit of energy equals 27.211 electron volts (eV) or 627.51 kcal/mole. 

The SI unit of dipole moment is the coulomb-meter (C m), but dipole moments for molecules are often more conveniently expressed in debye units (D), named for Peter Debye." The conversion factor is... 

It can be seen that the unit of dipole moment measurement is C m. This is a very large value and therefore a significantly smaller one is used in chemistry, namely 1 Debye (D) 1 D is equal to 3.33 X 10 ° C m. 

In stead, the electrostatic con tribn tion conies from definin g a set of bond dipole moments associated woth polar bonds. These bond moments are defined in the m m psir.LxL(dbf) file along with the bond stretching parameters and are given in units of Debyes. The cen ter of th e dipole Is defined to be th e m Idpoint of the bond an d two dipoles p. and pj. separated by Rjj. as shown beltnv ... 

Dipole moment (Section 1 5) Product of the attractive force between two opposite charges and the distance between them Dipole moment has the symbol p- and is measured in Debye units (D)... 

Figure 4 shows the measured angle of 105° between the hydrogens and the direction of the dipole moment. The measured dipole moment of water is 1.844 debye (a debye unit is 3.336 x 10 ° C m). The dipole moment of water is responsible for its distinctive properties in the Hquid state. The O—H bond length within the H2O molecule is 0.96 x 10 ° m. Dipole—dipole interaction between two water molecules forms a hydrogen bond, which is electrostatic in nature. The lower part of Figure 4 (not to the same scale) shows the measured H-bond distance of 2.76 x 10 ° m or 0.276 nm. 

The dipole moment p. is a molecular property defined as the product of charge (usually just a fraction of the electronic change, of course) and distance between the centers of positive and negative charge in the molecule. The dipole moment is usually expressed in debyes (D), where 1 D = 1(T esu in SI units 1 D = 3.3356 X 10 ° C-m. so, for example, the dipole moment of water is 1.84 D or 6.14 in units of 10 C-m. Again a rough correspondence is seen between this property of a molecule and its polarity, though e and p. are not precisely correlated. 

The symbols 5+ and 5- indicate polarity of the two ends or poles of the electrically neutral molecule. Such a polar molecule constitutes a permanent dipole, i.e., two equal and opposite charges (e) separated by a distance (d) in space. A quantitative measure of the polarity of a molecule is the dipole moment (p in Debye units), which is defined as the product of the charge (e in electrostatic units) and the distance (d in cm). 

---