Resolution dimensions

This is where two-dimensional (2D) spectroscopy comes into play, for example, by correlating one dimension where the anisotropic interactions are preserved with a (high-resolution) dimension where they are removed. That is, both objectives can be achieved within one two-dimensional experiment. Like conventional one-dimensional (ID) NMR techniques, 2D techniques were first applied to liquid or solutions, where they provided invaluable information for the structure assignments in biomolecules [7]. Later, after the... 

Table I. Order-of-Magnitude Comparison of Calculations for Capillary Column GC, Capillary Column SFC, Packed Column SFC, and Packed Column LC for Typical High Resolution Dimensions (d, = 250 ym, dp = 5 ym) and Best-Case Dimensions (d = 50 ym, dp = 3 ym). (Experimental values In Italics.)...

Residual Local Dipolar Fields by Heteronuclear Correlation Experiments. The NMR spectrum of rare spins (e.g. C) contains extremely useful information because of the usually high chemical-shift dispersion and the possibility to easily ehminate undesired spin interactions. It would thus be advantageous to combine this high resolution dimension with spectroscopy in form of... 

One of the more recent advances in XPS is the development of photoelectron microscopy [ ]. By either focusing the incident x-ray beam, or by using electrostatic lenses to image a small spot on the sample, spatially-resolved XPS has become feasible. The limits to the spatial resolution are currently of the order of 1 pm, but are expected to improve. This teclmique has many teclmological applications. For example, the chemical makeup of micromechanical and microelectronic devices can be monitored on the scale of the device dimensions. 

Advantages. Compared to DOR, a small rotor can be used allowing relatively fast spiiming speeds high RF powers can be attained and if the coil is moved with the rotor a good filling factor can be obtained. In the isotropic dimension high-resolution spectra are produced and the second dimension retains the anisotropic information. 

Interpretable high-resolution structural infomiation (e.g. preservation of dimensions, or correlation of the stmctiiral detail with a physiologically or biochemically controlled state) is therefore obtained exclusively from samples in which life has been stopped very quickly and with a sufficiently high time resolution for the cellular dynamics [19]. Modem concepts for specimen preparation therefore try to avoid traditional, chemical... 

Gc/ms is an example of a hyphenated instmment consisting of two techniques that provide orthogonal (independent) information. If two independent techniques are linked in tandem, a large number of data resolution elements is obtained from each. The more dimensions present, and the higher the available resolution along each dimension, the greater is the obtainable information (19). Because hyphenated systems generate an immense... 

Two-Dimensional Electrophoresis. Two-dimensional (2D) electrophoresis is unique, offering an analytical method that is both reproducible and sensitive. It is referred to as 2D because it employs two different methods of electrophoresis, in two different dimensions, to produce one result. Each method separates the sample compounds based on different properties of each compound. The combination of the two methods gives better resolution of the compounds in the sample than could be achieved with either method alone. For example, each method alone may separate up to 100 components of a sample, whereas together they may separate up to 10,000 components. 

A continuous lipidic cubic phase is obtained by mixing a long-chain lipid such as monoolein with a small amount of water. The result is a highly viscous state where the lipids are packed in curved continuous bilayers extending in three dimensions and which are interpenetrated by communicating aqueous channels. Crystallization of incorporated proteins starts inside the lipid phase and growth is achieved by lateral diffusion of the protein molecules to the nucleation sites. This system has recently been used to obtain three-dimensional crystals 20 x 20 x 8 pm in size of the membrane protein bacteriorhodopsin, which diffracted to 2 A resolution using a microfocus beam at the European Synchrotron Radiation Facility. 

The three-dimensional, digital nature of SFM and STM data makes the instruments excellent high-resolution profilometers. Like traditional stylus or optical profilometers, scanning probe microscopes provide reliable height information. However, traditional profilometers scan in one dimension only and cannot match SPM s height and lateral resolution. 

---