Probe, spectrometer

Here we will focus in detail on a UV pump-IR probe spectrometer described by Emsting and co-workers the system is based on an excimer laser and a dye laser operating with a pulse repetition rate ranging from 5 to 10 Hz. Pump pulses at 308 nm excite the sample and are followed at a selected time by probe IR pulses that range from 1950 to 4300 cm Absorbance changes can be recorded with a time resolution of 1.8 ps and with an accuracy in absorbance (A) of 0.001. 

Figure S> Schemaiic layout of an ultrafasl puaip-probe spectrometer. Top left panel A cw diode-pumped, Frequency-doubled, Nd YAO laser B mode-locked Ti-S oscillator C regenerative Ti-S amplilier D Q-switched, frequency-doubled Nd YLF amplifier pump laser E second/third-iiarmonic generators or OPA. Lower right panel F continuum generation G sample H CCD spectrograph. The double arrow indicates the optical delay stage, and the dashed tine indicates the pump-beam trajectory.

Transient spectroscopy experiments were performed with a pump-probe spectrometer [7] based on a home-made original femtosecond Ti saphire pulsed oscillator and a regenerative amplifier system operated at 10 Hz repetition rate. The Tirsaphire master oscillator was synchronously pumped with doubled output of feedback controlled mode-locked picosecond pulsed Nd YAG laser. The pulse width and energy of Ti saphire system after the amplifier were ca. 150 fs and 0.5 mJ, respectively, tunable over the spectral range of 760-820 nm. The fundamental output of the Ti saphire system (790 nm output wavelength was set for present study) splitted into two beams in the ratio 1 4. The more intense beam passed through a controlled delay line and was utilized for sample... 

The transient absorption setup used in our experiments is a versatile tool providing both the necessary time resolution and the tunability to investigate different compounds. The pump-probe spectrometer is based on two noncollinearly phase matched optical parametric amplifiers (NOPAs) (see Fig. 11.3) [21, 22]. The NOPAs are pumped by a regenerative Ti sapphire laser amplifier delivering approximately 100 fs NIR pulses at around 800 nm with a repetition rate of 1 kHz. 

ICP analyses were performed by Plasma Absorption Emission Spectroscopy (ICP-AES). BET surface areas were measured with a Micromeritics TriStar 3000 instrument after degassing the samples at 150 C under a 0.13 Pa vacuum overnight. XPS analyses were performed on a SSI X-probe spectrometer (SSX-100/206 photoelectron spectrometer Fisons) equipped with a monochromatized microfocused Al Ka X-ray source (1486.6 eV) and a hemispherical analyser. The binding energies were calculated relative to the C-(C, H) component of the adventitious Cls carbon peak fixed at 284.8 eV. Zeta potential measurements were carried out in a PENKEM Zeta Meter 500, using 25 mg of sample ultrasonically dispersed in 200 ml of an aqueous solution... 

SSI X probe spectrometer (model SSXlOO) using a monochromatic A1 Ka radiation (1486 eV). Temperature programmed reduction was carried out with a quadrupole Balzers spectrometer QMS 311 100 mg of catalyst mixed with 100 mg of Pt/AlaOa were put in a U-shaped tubular quartz reactor and heated under H2 flow (5% in N2, 60 ml/min) from room temperature to 750°C with a heating rate of 5°C/min. Raman spectra were collected with a Perkin Elmer System 2000 NIR FT-Raman using as excitation radiation the 5 harmonic of a diode pumped Nd YAG laser (1065 nm). 

Ions are also used to initiate secondary ion mass spectrometry (SIMS) [ ], as described in section BI.25.3. In SIMS, the ions sputtered from the surface are measured with a mass spectrometer. SIMS provides an accurate measure of the surface composition with extremely good sensitivity. SIMS can be collected in the static mode in which the surface is only minimally disrupted, or in the dynamic mode in which material is removed so that the composition can be detemiined as a fiinction of depth below the surface. SIMS has also been used along with a shadow and blocking cone analysis as a probe of surface structure [70]. 

Another problem in many NMR spectrometers is that the start of the FID is corrupted due to various instrumental deadtimes that lead to intensity problems in the spectrum. The spectrometer deadtime is made up of a number of sources that can be apportioned to either the probe or the electronics. The loss of the initial part of the FID is manifest in a spectrum as a rolling baseline and the preferential loss of broad components of... 

The heart of an NMR spectrometer is the probe, which is essentially a tuned resonant circuit with the sample contained within the main inductance (the NMR coil) of that circuit. Usually a parallel tuned circuit is used with a resonant frequency of coq = The resonant frequency is obviously the most important probe... 

Figure B2.1.6 Femtosecond spectrometer for transient hole-burning spectroscopy with a continuum probe. Symbols used bs, 10% reflecting beamsplitter p, polarizer. The continuum generator consists of a focusing lens, a cell containing flowing water or ethylene glycol or, alternatively, a sapphire crystal and a recollimating lens.

Liquids examined by FAB are introduced into the mass spectrometer on the end of a probe inserted through a vacuum lock in such a way that the liquid lies in the target area of the fast atom or ion beam. There is a high vacuum in this region, and there would be little point in attempting to examine a solution of a sample in one of the commoner volatile solvents such as water or dichloromethane because it would evaporate extremely quickly, probably as a burst of vapor when introduced into the vacuum. Therefore it is necessary to use a high-boiling solvent as the matrix material, such as one of those listed in Table 13.1. 

By passing a continuous flow of solvent (admixed with a matrix material) from an LC column to a target area on the end of a probe tip and then bombarding the target with fast atoms or ions, secondary positive or negative ions are ejected from the surface of the liquid. These ions are then extracted into the analyzer of a mass spectrometer for measurement of a mass spectrum. As mixture components emerge from the LC column, their mass spectra are obtained. 

Continuous inlet. An inlet in which sample passes continuously into the mass spectrometer ion source, as distinguished from a reservoir inlet or a direct-inlet probe. 

Direct-exposure probe. Provides for insertion of a sample on an exposed surface, such as a flat surface or a wire, into (rather than up to the entrance of) the ion source of a mass spectrometer. 

Direct-inlet probe. A shaft or tube having a sample holder at one end that is inserted into the vacuum system of a mass spectrometer through a vacuum lock to place the sample near to, at the entrance of, or within the ion source. The sample is vaporized by heat from the ion source, by heat applied from an external source, or by exposure to ion or atom bombardment. Direct-inlet probe, direct-introduction probe, and direct-insertion probe are synonymous terms. The use of DIP as an abbreviation for these terms is not recommended. 

Vacuum-lock inlet. An inlet through which a sample is first placed in a chamber the chamber is then pumped out, and a valve is opened so that the sample can be introduced to the mass spectrometer ion source. A vacuum-lock inlet commonly uses a direct-inlet probe, which passes through one or more sliding seals, although other kinds of vacuum-lock inlets are also used. 

Fig. 6. Spectra of 2-methyl-5-bromopentaiie acquired using a Bruker 300AMX spectrometer (a) TOCSY using a 5-mm dual probe and (b) HMQC...

Fig. 7. Nmr spectra of quinine [103-95-0] C2QH24N2O2, acquired on a Bruker 300AMX spectrometer using a Bmker broadband CP/MAS probe, (a) Proton-decoupled spectmm of quinine in CDCl (b) the corresponding spectmm of solid quinine under CP/MAS conditions using high power dipolar decoupling (c) soHd-state spectmm using only MAS and dipolar decoupling, but without cross-polarization and (d) soHd quinine mn using the...

In the remainder of this section, we compare EISFs and Lorentzian line widths from our simulation of a fully hydrated liquid crystalline phase DPPC bilayer at 50°C with experiments by Kdnig et al. on oriented bilayers that, in order to achieve high degrees of orientation, were not fully hydrated. We consider two sets of measurements at 60°C on the IN5 time-of-flight spectrometer at the ILL one in which the bilayer preparations contained 23% (w/w) pure D2O and another in which bilayer orientation was preserved at 30% D2O by adding NaCl. The measurements were made on samples with two different orientations with respect to the incident neutron beam to probe motions either in the plane of the bilayers or perpendicular to that plane. 

In Surface Analysis by Laser Ionization (SALI), a probe beam such as an ion beam, electron beam, or laser is directed onto a surfiice to remove a sample of material. An untuned, high-intensity laser beam passes parallel and close to but above the sur-fiice. The laser has sufficient intensity to induce a high degree of nonresonant, and hence nonselective, photoionization of the vaporized sample of material within the laser beam. The nonselectively ionized sample is then subjected to mass spectral analysis to determine the nature of the unknown species. SALI spectra accurately reflect the surface composition, and the use of time-of-flight mass spectrometers provides fast, efficient and extremely sensitive analysis. 

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