Spectrum, amplitude

SWEEP OFFSET (Hz) SPECTRUM AMPLITUDE INTEGRAL AMPLITUDE SPINNING RATE (RPS) ... 

Figure 9.1 Spectrum recorded during the decomposition of a solution of propionyl benzoyl peroxide and iodine in o-dichlorobenzene at 100°C. The numbers in parentheses below the formulas indicate the relative spectrum amplitudes for the underlined protons. Spectrum groups referred to in the text are indicated at the top of the figure. Reprinted with permission from H. R. Ward, Accts. Chem. Res., 5, 18 (1972). Copyright by the American Chemical Society.

Fig. 7.3. a Target spectrum amplitude of a normal double pulse corresponding to Fig. 7.2, and b the mask function added to the AOPDF after two iterations [7]... 

FIC. 6 Proton nmr spectrum of 2-methyl-3-pentanol containing Eu(dpm)3 (60 MHz). Mole ratio of Eu(dpm)3 to alcohol = 1.0. Compare this spectrum to those shown in Fig. 5. Protons nearest the hydroxyl group are shifted most. Methyl groups are recorded at reduced spectrum amplitude. Note the large chemical shift difference between the two protons on C-4. The average conformation of the molecule is the one shown and was calculated from the equation on p. 219. 

Fig. 6. Theoretical integrated reduction factor of the powder spectrum (amplitude at the top of solid echo) for a two-site jump motion (Pa=Pb) as the function of jump frequency 1/Tc and for different jump angles 2/ . (Reprinted with permission from Ref. 112. Copyright 1990 American Chemical Society.)...

Figure 3. NMR Spectrum of Dexamethasone in Deuterated Pyridine Operating Conditions Signal 60 MHz Sample Merck Std. 8415-76, 51.5 mg./.5 cc. of C5D5N, Sweep Time 250 sec. Spectrum Amplitude 1,25 X 10-Internal Standard Tetramethylsilone...

Rectangular pulse Continuous, smoothly varying phase and amplitude spectrum. Amplitude spectrum characterized by decreasing magnitudes as frequency increases and by periodic zero-amplitude nodes. 

Figure 8.9 Top Periodic waveform with a line harmonic frequency spectrum. Bottom Nonperiodic waveform has a continuous frequency spectrum. Line spectrum amplitude [volt]. Continuous spectrum amplitude [volt y s ].

Records of large earthquakes and/or from soft sites usually feature larger motions at low frequencies than records of small events and/or from rock sites. Figure 8 displays the Fourier spectrum amplitude of two acceleration signals recorded at AQV for two events of magnitude M 5.1 and M 6.3, located at the same distance from the station. 

During the inspection of an unknown object its surface is scanned by the probe and ultrasonic spectra are acquired for many discrete points. Disbond detection is performed by the operator looking at some simple features of the acquired spectra, such as center frequency and amplitude of the highest peak in a pre-selected frequency range. This means that the operator has to perform spectrum classification based on primitive features extracted by the instrument. 

Figure 5. Amplitude-phase characteristics of the model for visco-elasto-plastic (left column) and brittle (right column) materials 1- spectrum responses 2- TF models.

The instrument uses a sinusoidal driver. The spectrum is very clean as we use a 14 bits signal generator. The probe signal is modulated in amplitude and phase by a defect signal. The demodulation is intended to extract the cartesian values X and Y of this modulation. 

For immersion probes we also get similar improvements using piezocomposite transducers as demonstrated by the third example. In Fig. 8 we compare pulse form and frequency spectrum for a 2 MHz probe Z2K with 10 mm transducer diameter. The echo of the composite probe has 11 dB more amplitude and is clearly shorter than for the old design, also indicated by the increase in bandwidth from 45 to 76 %. 

In electron spin echo relaxation studies, the two-pulse echo amplitude, as a fiinction of tire pulse separation time T, gives a measure of the phase memory relaxation time from which can be extracted if Jj-effects are taken into consideration. Problems may arise from spectral diflfrision due to incomplete excitation of the EPR spectrum. In this case some of the transverse magnetization may leak into adjacent parts of the spectrum that have not been excited by the MW pulses. Spectral diflfrision effects can be suppressed by using the Carr-Purcell-Meiboom-Gill pulse sequence, which is also well known in NMR. The experiment involves using a sequence of n-pulses separated by 2r and can be denoted as [7i/2-(x-7i-T-echo) J. A series of echoes separated by lx is generated and the decay in their amplitudes is characterized by Ty. ... 

The mass spectrometer provides a mass spectrum that is actually an analog voltage varying in amplitude with time as ions of different m/z values arrive at the ion collector within a period of a few seconds. An important exception to this generalization occurs with ion collectors, called time-to-digital converters because their output is already digitized. 

Conceptually, the problem of going from the time domain spectra in Figures 3.7(a)-3.9(a) to the frequency domain spectra in Figures 3.7(b)-3.9(b) is straightforward, at least in these cases because we knew the result before we started. Nevertheless, we can still visualize the breaking down of any time domain spectrum, however complex and irregular in appearance, into its component waves, each with its characteristic frequency and amplitude. Although we can visualize it, the process of Fourier transformation which actually carries it out is a mathematically complex operation. The mathematical principles will be discussed only briefly here. 

The Q and ft) dependence of neutron scattering structure factors contains infonnation on the geometry, amplitudes, and time scales of all the motions in which the scatterers participate that are resolved by the instrument. Motions that are slow relative to the time scale of the measurement give rise to a 8-function elastic peak at ft) = 0, whereas diffusive motions lead to quasielastic broadening of the central peak and vibrational motions attenuate the intensity of the spectrum. It is useful to express the structure factors in a form that permits the contributions from vibrational and diffusive motions to be isolated. Assuming that vibrational and diffusive motions are decoupled, we can write the measured structure factor as... 

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