Resonance ionization utility

Figure 1C. Periodic table depicting utility of RIMS, a. Elements for which resonance ionization feasibility has been demonstrated at NBS using thermal atomization b> elements for which ionization feasibility has been demonstrated in other laboratories using resonance ionization mass spectrometry (38-Ul> UU-32) c, elements for which isotope dilution RIMS have been achieved at NBS and d, potentially applicable for resonance ionization via two and three photon processes (Schemes 1, 2, and 5 of Figure U), using the BIMS system in Figure 6.

Since these mass discrimination effects are largely a function of the vaporization process the same discrimination and correction techniques would be applicable to the resonance ionization processes that utilize thermal vapor sources ... 

Photoionization, where electrons are released by molecules following the absorption of energy from photons, has long been viewed as a non-radioactive means to ionize explosives in the vapor phase [39]. In recent years, two teams have sought to employ laser ionization with IMS for explosive determinations. A team at Implant Sciences Corporation has utilized a laser (or flash lamp) for sampling surfaces and for ionization of sample vapors in an IMS analyzer [40, 41]. In their approach, the sample is removed from a surface with an increased temperature from laser exposure. Gases (and presumably particulate matter) from over the surface are drawn into an IMS drift tube using a wall-free inlet vida supra). In the IMS drift tube, resonance multi-photon ionization by a laser is used to produce ions from the explosives. Their... 

Atmospheric pressure laser ionization (APLl) is a complementary technique to existing API methods. It is based on resonant or near-resonant two-photon ionization of aromatic ring systems. APLI utilizes resonantly enhanced multiphotonionization (REMPI) as the primary ion-production mechanism, nevertheless it occurs at atmospheric pressure [80],... 

The thermal instability of Baj.xKxBiOj compounds makes it desirable to utilize low temperature deposition techniques. Use of a three cell evaporation source coupled with oxygen, ionized by an electron cyclotron resonance source and accelerated toward the... 

Recently, new 2D-methods for the analysis of complex mixtures have been developed for time-of-flight mass spectrometry (22), which could also be utilized in external ionization FTMS. Specifically, the combination of IR-laser desorption of nonvolatile neutrals, followed by adiabatic cooling to 2°K in a supersonic jet, and subsequent compound-selective Resonance-Enhanced Multiphoton Ionization (REMPI) could increase the role of FTMS in the analysis of biological mixtures. The coupling of supersonic jets to the external ion source would also be of interest in ion- and neutral cluster experiments. 

The present results demonstrate the utility of electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry (ESI FT-ICR MS) for analysis of hydrogen/deuterium exchange to determine the number of... 

Equations 6.100 and 6.102 with ts = te = 1, t = / have been solved for real air in Ref. 16 and in Refs. 51-55, with the latter references utilizing the concept of total properties kT, cpT, Prr. The air properties of Ref. 56 were employed in all the studies except that of Ref. 55, which employed properties evaluated in Refs. 57 and 58, where careful consideration was given to the effect of dominant resonant charge exchange cross sections in establishing the thermal conductivity of ionized nitrogen. 

Multiphoton ionization spectroscopy has been reviewed in two recent articles. An apparatus has been described for constant intensity multiphoton ionization spectroscopy. A sensitive molecular vapour detection system utilizing resonance-enhanced two-photon ionization has been used to monitor naphthalene to a limit of 5 x 10 molecules cm Excitation was achieved... 

This resonance-stabilized, mustard-like antineoplastic agent utilizes an estradiol carrier (Fig. 42.3) to selectively deliver drug to steroid-dependent prostate tissue, and its use is limited to the palliative treatment of progressive prostate cancer. The essential 17P-OH group has been esterified with phosphoric acid, and the C3-phenol has been carbamylated. The body still, however, transports the basic steroidal pharmacophore into cells. The ionized sodium phosphate ester of the active 17P-OH group makes the compound water soluble and able to distribute in the blood. The ester is readily cleaved during absorption to provide the active 17(3-OH. 

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