Off resonance

Cho M 1997 Off-resonant coherent hyper-Raman scattering spectroscopy J. Chem. Phys. 106 7550-7... 

A far-off resonance trap (FORT), in contrast, uses tire dipole force ratlier tlian tire spontaneous force to confine atoms and can therefore operate far from resonance witli negligible population of excited states. A hybrid MOT/dipole-force trap was used by a NIST-Maryland collaboration [26] to study cold collisions, and a FORT was... 

Figure C3.2.16. Dependence of measured resistance in an STM junction consisting of a bare tip a tip with one Xe atom attached, and a tip with two Xe atoms. Note that the Xe atoms facilitate tunnelling (compared to empty space). From Yazdani A, Eigler D M and Lang N D 1996 Off resonance conduction tlirough atomic wires Science 111 1921-4.

Materials are also classified according to a particular phenomenon being considered. AppHcations exploiting off-resonance optical nonlinearities include electrooptic modulation, frequency generation, optical parametric oscillation, and optical self-focusing. AppHcations exploiting resonant optical nonlinearities include sensor protection and optical limiting, optical memory appHcations, etc. Because different appHcations have different transparency requirements, distinction between resonant and off-resonance phenomena are thus appHcation specific and somewhat arbitrary. 

Decoupling (Section 13.17) In NMR spectroscopy, any process that destroys the coupling of nuclear spins between two nuclei. Two types of decoupling are employed in C NMR spectroscopy. Broadband decoupling removes all the couplings off-resonance decoupling removes all H- C couplings except those between directly bonded atoms. 

In the FOIST based selective control, it is the or the which are transported to the excited electronic states. In the case of IBr, the B( IIo) state is coupled four times more strongly with the ground state (/ioi = 0.25/to2) as compared to the state. Also, the state is far off resonance... 

As mentioned already, the INEPT spectra are typified by the antiphase character of the individual multiplets. The INEPT C-NMR spectrum of 1,2-dibromobutane is shown, along with the normal off-resonance C-NMR spectrum, in Fig. 2.12. Doublets show one peak with positive phase and the other with negative phase. Triplets show the outer two peaks with positive and negative amplitudes and the central peak with a weak positive amplitude. Quartets have the first two peaks with positive amplitudes and the remaining two peaks with negative amplitudes. 

How can spectral editing in INEPT be used to generate separate spectra for CH, CH2, and CH3 groups, and how is it superior to the traditional off-resonance decoupled spectra ... 

The most widely used method for determining multiplicities of carbon atoms is DEPT (Distortionless Enhancement by Polarization Transfer). This has generally replaced the classical method of recording off-resonance C spectra with reduced CH couplings from which the multiplicity could be read directly. 

In our tip-enhanced near-field CARS microscopy, two mode-locked pulsed lasers (pulse duration 5ps, spectral width 4cm ) were used for excitation of CARS polarization [21]. The sample was a DNA network nanostructure of poly(dA-dT)-poly(dA-dT) [24]. The frequency difference of the two excitation lasers (cOi — CO2) was set at 1337 cm, corresponding to the ring stretching mode of diazole. After the on-resonant imaging, CO2 was changed such that the frequency difference corresponded to none of the Raman-active vibration of the sample ( off-resonant ). The CARS images at the on- and off- resonant frequencies are illustrated in Figure 2.8a and b, respectively. 

A spontaneous Raman spectra is shown in Figure 2.8d in which the on- and off-resonant frequencies are indicated. The DNA bundles are observed at the resonant frequency, as shown in Figure 2.8a, while they cannot be seen at the off-resonant frequency in Figure 2.8b. This indicates that the observed contrast is dominated by the vibrationally resonant CARS signals. Figure 2.8c shows a cross-section of Figure 2.8a denoted by two solid arrows, which were acquired with a 5 nm step. The FWHM of... 

Since the resonance absorption vanishes for d oo, the count rate off resonance is given entirely by mass absorption... 

In the study of 13C-NMR spectra of 8 and 6, the presence of the hydroxyl group at C-14 is also evident since a downfield shift of 43 ppm from 6 (<521.2) to 8 (<563.87) is observed. The previously ambiguous assignments of C-15, C-16, C-5, and C-20 are also clarified through irradiation of H-16, H-5, and H-20 with low-power single-frequency off-resonance decoupling (SFORD) experiments. 

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