What is "debye"

n. (context physics English): A CGS unit of electrical dipole moment equivalent to 3.33564 x 10^-30 coulomb meter, used for measurements at the molecular scale.

The debye (symbol: D) (; ) is a CGS unit (a non- SI metric unit) of electric dipole momentElectric dipole moment is defined as charge times displacement:

p = qr named in honour of the physicist Peter J. W. Debye. It is defined as 1 statcoulomb- centimetre.The statcoulomb is also known as the franklin or electrostatic unit of charge.

:{| |1 statC ||=1 Fr |- | ||=1 esu |} Historically the debye was defined as the dipole moment resulting from two charges of opposite sign but an equal magnitude of 10 statcoulomb (generally called e.s.u. (electrostatic unit) in older literature), which were separated by 1 ångström.The ångström is of an order of magnitude close to that of a typical covalent bond.

:{| |- |1 Å ||= 100 pm |- | ||= 10 cm |- | ||= 10 m |} This gave a convenient unit for molecular dipole moments.

:{| |- |height=30|1 D ||= 10 statC·cm |- |height=30| |= 10 esu·Å |- |height=30| |= C· m |- |height=30| |≈ 3.33564 C·m |- |height=30| |≈ 1.10048498 ql |- |height=30| |≈ 0.393430307 ea |- |height=30| |≈ 0.20819434 eÅ |}

Typical dipole moments for simple diatomic molecules are in the range of 0 to 11 D. Symmetric homoatomic species, e.g. chlorine, Cl, have zero dipole moment and highly ionic molecular species have a very large dipole moment, e.g. gas phase potassium bromide, KBr, with a dipole moment of 10.5 D.

The debye is still used in atomic physics and chemistry because SI units are inconveniently large. The smallest SI unit of electric dipole moment is the yoctocoulomb-metre, which is roughly 300,000 D. There is currently no satisfactory solution to this problem of notation without resorting to the use of scientific notation.

Debye is a lunar crater that is located in the northern hemisphere on the Moon's far side, as seen from the Earth. It lies to the south of the crater Chappell, to the southwest of the walled plain Rowland, and to the east of D'Alembert.

The outer rim of this crater has been heavily battered by impacts, and is somewhat distorted from the form of a circle. The northeast rim in particular has become straightened by impact modification, and the crater rim as a whole has a roughly polygonal shape. The southern rim is overlaid by the smaller crater Perkin. The most heavily eroded section of the rim is along the northeast, where a cluster of overlapping craters intrudes into the side. The western rim is notched and indented by several small impacts.

The crater interior is nearly as battered as the outer rim. The outer rampart of Perkin intrudes part way across the southern floor. Parts of remaining interior have been bombarded and churned by impacts, leaving an irregular surface that is nearly as rough as the terrain that surrounds the crater. The most recent of these impacts is a small, cup-shaped crater just to the southwest of the midpoint.

Debye may refer to:

• Peter Debye (1884–1966), Dutch physicist, physical chemist and Nobel laureate in Chemistry
  • Debye, a non-SI unit of electric dipole moment, 3.33564 C·m, named after Peter Debye
  • Debye (crater), a lunar crater named after Peter Debye
  • 30852 Debye, a main-belt asteroid named after Peter Debye