SIMS, definition

With today s technology, the definition of the surface as it effects a material s performance in many cases means the outer one or two monolayers. It is the specific chemistry of these immediate surface molecules that determines many of the chemical and physical properties. Therefore, it is important to have available a tool that is able to characterize the chemistry of these layers. One such method that has met with considerable success is Static Secondary Ion Mass Spectrometry (SIMS). 

Malunowicz EM, Mitkowska Z, Bal K, Nizankowska-Blaz T, Moszczynska E, Iwanicka Z, Romer (1997) Definitive diagnosis of enzymatic deficiencies of steroidogenesis in at-risk newborns and infants by urinary marker analysis using GC/MS-SIM. Horm Res 48 243-251... 

Figure 4. The positive ion TOF SIMS spectra for the HAPS-coated E-glass slides. See text for definitions.

Equations (3) and (4) are formally identical with the earlier Kubelka s hyperbolic solutions of differential equations for forward and backward fluxes (11), although the Chandrasekhar-Klier and Kubelka s theories start from different sets of assumptions and employ different definitions of constants characterizing the scattering and absorption properties of the medium. In Kubelka s theory, the constants a, b, and Y are related to the Schuster-Kubelka-Munk (SIM) absorption K and scattering S coefficients as... 

The method of defining RSFs described is traditional in analytical chemistry, generates RSFs without units, results in larger numbers for elements for which the SIMS instrument is more sensitive, and is essentially the same as Wittmaack s proposed use of scaled sensitivity ratios [100]. However, an alternative definition of sensitivity factors that has gained much popularity with semiconductor specialists is that of Wilson [69,101] ... 

With this definition, RSF has units of atoms per cubic centimeter, and an element that is detected with more sensitivity in the SIMS instrument has a smaller RSF. 

Thus the SIMS analyst must be aware of the definition of RSF being used when reading the literature. 

We recall that in the simulation (dots in Fig. 6) C and B were, respectively, 25 and 38 Hz. The applied field was assumed to be perfectly homogeneous and C originated entirely from the finite width of the pulses. The fact that the experimental value of B is smaller than that derived from the simulations is not surprising because the simulations were carried out for the crystal orientation where the dipolar coupling of the methylene protons has its absolute maximum, whereas the experiment was done for a different, alas unknown, orientation. For this orientation the dipolar coupling was definitely even smaller than the maximum accessible with our arbitrarily fixed sample crystal, which itself is smaller than the absolute maximum, as can be inferred from a comparison of the t = 1.5-/1S spectrum in Fig. 23 with the MREV spectrum in Fig. 22a. In any event the result B p < B - is pleasing and gives credit to our spectrometer (the indices exp and sim mean experimental and simulated). From B < B it also follows that the finite-pulsewidth contribution to is smaller... 

Recall that Sim works on inputs of the form (par, K, auXyi ), like V. For simplicity, Sim is required to output triples (acc, acc observed, auxyg f) like ZKPp y, although this means that Sim simulates both V and Obs, instead of V only. This does not make the definition stricter, because any combination of V and Obs is another admissible cheating verifier V. ... 

Proof. Correct generation follows from the precondition on gen. Effectiveness of proofs follows immediately from the precondition [Corr, c Goodj fj. Soundness is just the definition of V. Zero-knowledge is clear because P does not send anything, hence it cannot divulge anything formally, one can use Sim = V. The external verifiability requirement of the prover is shown like the effectiveness of proofs, and the external verifiability requirement of the verifier is fulfilled because Obs = V and both are deterministic. ... 

In the context of the NMR-SIM simulation, the recording of a one-dimensional experiment consists of the definition of the spin system, the pulse sequence and the experiment parameters. The result of the simulation is a FID that is loaded into the ID WIN-NMR processing program. Both the time domain and the frequency domain data may be processed using a variety of domain specific mathematical functions. 

In the first section of this chapter spin systems and pulse sequences are discussed. Starting with the definition of a spin system and a description of the various spin parameters used by NMR-SIM. Using suitable examples the correct definition of spin system parameters, how to reduce the number of spin system parameters and the application of variable spin system parameters is illustrated. Following on, pulse sequences are discussed in some detail and the difference between a pulse sequence and a pulse program is emphasized. The pulse program language of NMR-SIM should be familiar to users of Bruker NMR spectrometers as it uses the same syntax. However, because this is not covered in the NMR-SIM manual, pulse sequence elements such as pulses, phases and delays are explained in detail and illustrated using a variety of examples. 

This chapter can be used either as an introduction to spin system definition and pulse programming or as a reference section. In either case the emphasis is on "learning by doing" and to this end there are numerous examples and Check its to follow. It is recommended that readers unfamiliar with simulation experiments refer to sections 2.2.2 and 2.3.2 before starting this chapter. This teaching version of NMR-SIM does not have all the features of the full version, consequently some topics that appear in the full version may not appear in this text and in these cases the NMR-SIM manual should be consulted for further information. 

The labels used in the definition of the NMR-SIM spin system parameters depend to some extent upon personal preference. As with any programming language it is important to include comments comments not only makes the spin system file more readable, they also make it easier to keep track of any modifications to the file and help other users to understand the spin system definitions. Comment lines start with a semicolon ( ) and both the semicolon and the following text are ignored by the NMR-SIM processor. 

In NMR-SIM, simulations are based on the definition of either a single spin system or two or more spin systems. The simultaneous simulation of several independent spin systems becomes relevant if molecules with two or more mutually isolated spin systems are investigated or if the spectrum of two or more compounds have to be described. In the latter case it is also necessary to include the concentration ratio for the correct correlation of intensities and integrals. Even for a chemically pure compound the definition of several spin systems is necessary to completely define the molecule if the structure contains NMR active isotope of low natural abundance e.g. NMR-SIM... 

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