TAI as a time scale is a weighted average of the time kept by over 200 atomic clocks in over 50 national laboratories worldwide.

The latter is not to be confused with TA ( NPL ), which denotes an independent atomic time scale, not synchronised to TAI or to anything else.

This time scale is expressed in the form of tables of differences UTC-UTC ( k ) ( equivalent to TAI-TAI ( k )) for each participating institution k. ( The same circular also gives tables of TAI-TA ( k ), for the various unsynchronised atomic time scales.

The United States Naval Observatory began the A. 1 scale 13 September 1956, using an Atomichron commercial atomic clock, followed by the NBS-A scale at the National Bureau of Standards, Boulder, Colorado.

UTC is a discontinuous time scale composed from segments that are linear transformations of atomic time, the discontinuities being arranged so that UTC approximated UT2 until the end of 1971, and UT1 thereafter.

This was a compromise arrangement for a broadcast time scale: a linear transformation of the BIH's atomic time meant that the time scale was stable and internationally synchronised, while approximating UT1 means that tasks such as navigation which require a source of Universal Time continue to be well served by public time broadcasts.

On the atomic scale, area is measured in units of barns, such that:

Even amorphous materials have some short-range order at the atomic length scale due to the nature of chemical bonding.

Computer methods are utilised to rebuild a three dimensional view of the sample, prior to it being evaporated, providing atomic scale information on the structure of a sample, as well as providing the type atomic species information.

A key feature of the evaporation or field ion images is that the data density is highly inhomogeneous, due to the corrugation of the specimen surface at the atomic scale.

The Copenhagen interpretation is a consensus among some of the pioneers in the field of quantum mechanics that it is undesirable to posit anything that goes beyond the mathematical formulae and the kinds of physical apparatus and reactions that enable us to gain some knowledge of what goes on at the atomic scale.

Its successor time scales, such as TDT, as well as the atomic time scale IAT ( TAI ), were designed with a relationship that " provides continuity with ephemeris time ".

The atomic clocks gave rise to the atomic time scale, and to what was first called Terrestrial Dynamical Time and is now Terrestrial Time, defined to provide continuity with ET.

The development of the atomic force microscope ( 1986 ) has recently enabled scientists to study friction at the atomic scale.

The very high spatial resolution and high contrast for features on the atomic scale arises from the fact that the electric field is enhanced in the vicinity of the surface atoms because of the higher local curvature.

To summarize the arguments against feasibility: First, critics argue that a primary barrier to achieving molecular nanotechnology is the lack of an efficient way to create machines on a molecular / atomic scale, especially in the absence of a well-defined path toward a self-replicating assembler or diamondoid nanofactory.

Vertically, the molecular gas inhabits the narrow midplane of the Galactic disc with a characteristic scale height, Z, of approximately 50 – 75 parsec, much thinner than the warm atomic ( Z = 130 – 400 pc ) and warm ionized ( Z = 1000 pc ) gaseous components of the ISM.

In addition to describing the motion of atomic level phenomena, quantum mechanics is useful in understanding some large scale phenomenon such as superfluidity, superconductivity, and biological systems, including the function of smell receptors and the structures of proteins.

Nanotechnology ( sometimes shortened to " nanotech ") is the manipulation of matter on an atomic and molecular scale.

Nanotechnology is very diverse, ranging from extensions of conventional device physics to completely new approaches based upon molecular self-assembly, from developing new materials with dimensions on the nanoscale to direct control of matter on the atomic scale.

Examples of scanning probe microscopes are the atomic force microscope ( AFM ), the Scanning tunneling microscope and the photonic force microscope.

The scanning tunneling microscope, an instrument for imaging surfaces at the atomic level, was developed in 1981 by Gerd Binnig and Heinrich Rohrer at IBM Zurich Research Laboratory, for which they received the Nobel Prize in Physics in 1986.

These ideas were later realized by the use of the scanning tunneling microscope, the atomic force microscope and other examples of probe microscopy and storage systems such as Millipede, created by researchers at IBM.

A scanning tunneling microscope ( STM ) is an instrument for imaging surfaces at the atomic level.

These include photon scanning microscopy ( PSTM ), which uses an optical tip to tunnel photons ; scanning tunneling potentiometry ( STP ), which measures electric potential across a surface ; spin polarized scanning tunneling microscopy ( SPSTM ), which uses a ferromagnetic tip to tunnel spin-polarized electrons into a magnetic sample, and atomic force microscopy ( AFM ), in which the force caused by interaction between the tip and sample is measured.

He discovered a theoretical explanation of alpha decay via quantum tunneling, and worked on radioactive decay of the atomic nucleus, star formation, stellar nucleosynthesis and Big Bang nucleosynthesis ( which he collectively called nucleocosmogenesis ), the cosmic microwave background, and molecular genetics.

To keep this explanation of Fowler-Nordheim tunneling relatively simple, these assumptions are needed ; but the atomic structure of matter is in effect being disregarded.

The structures of SAMs are commonly determined using scanning probe microscopy techniques such as atomic force microscopy ( AFM ) and scanning tunneling microscopy ( STM ).

" Scanning probe microscopy, including atomic force microscopy and scanning tunneling microscopy, is used as primary instrumentation to image / interrogate surfaces with novel and unexpected properties.

Scanning tunneling spectroscopy ( STS ) is an experimental technique which uses a scanning tunneling microscope ( STM ) to probe the local density of electronic states ( LDOS ) and the band gap of surfaces and materials on surfaces at the atomic scale.

He pioneered the use of scanning tunneling microscopy and spectroscopy to study surface chemistry on the atomic scale, and establish the relation between chemical reactivity and local electronic structure.

Bifurcation theory has been applied to connect quantum systems to the dynamics of their classical analogues in atomic systems, molecular systems, and resonant tunneling diodes.

The characteristic color of copper results from the electronic transitions between the filled 3d and half-empty 4s atomic shells – the energy difference between these shells is such that it corresponds to orange light.

In a quantum mechanical description of atomic structure, this period corresponds to the filling of the 2s and 2p orbitals.

In a quantum mechanical description of atomic structure, this period corresponds to the filling of the 1s orbital.

* A visualization of all common and uncommon atomic orbitals, from 1s to 7g ( Note that the radial part of the expressions given corresponds to Slater orbitals rather than Gaussians.

Each full period corresponds to formation of a single atomic layer thin film.

# The arrangement of the elements, or of groups of elements in the order of their atomic masses, corresponds to their so-called valencies, as well as, to some extent, to their distinctive chemical properties ; as is apparent among other series in that of Li, Be, Ba, C, N, O, and Sn ( should be Li, Be, B, C, N, O, and F ).

Quantum mechanically, this corresponds to mixing orbitals that differ in the l and m quantum numbers, such as the s ( l = 0 ) and p ( l = 1 ) atomic orbitals.

Similarly the set of all sets of atomic sentences corresponds to the set of all possible worlds ( all that could be the case ).

In atomic physics, Hund's rules refer to a set of rules formulated by German physicist Friedrich Hund around 1927, which are used to determine the term symbol that corresponds to the ground state of a multi-electron atom.

Antonius Johannes van den Broek ( 4 May 1870, Zoetermeer-25 October 1926, Bilthoven ) was a Dutch amateur physicist notable for being the first who realized that the number of an element in the periodic table corresponds to the charge of its atomic nucleus.