Infrared spectroscopy irradiation

To evaluate the reactivity of model compounds III-VIII in photoinitiated cationic polymerization, we have employed real-time infrared spectroscopy (RTIR). Thin film samples of the model compounds containing 0.5 mol% of (4-n-octyloxyphenyl)phenyliodonium SbF - as a photoinitiator were irradiated in a FTIR spectrometer at a UV intensity of 20 mW/cm2. During irradiation, the decrease in the absorbance of the epoxy ether band at 860 cm-1 was monitored. 

Formic acid irradiation of, 3 183 reaction with hydrogen atom, 3 191 Formylium cation, 9 231 Formylmethanofuran dehydrogenase, Methano-bacterium wolfei, 40 73 Fossil fuel, radiocarbon and, 3 311-312 Four-coordinated metal centers, 37 19 Fourier-transform infrared spectroscopy, NiFe hydrogenase, 47 295-298, 299, 303 Fourier-transform ion cyclotron resonance... 

Infrared and Raman spectroscopy. Stephens and Price (1970, 1972) used infrared spectroscopy to examine both ambient and laboratory-generated aerosols. They identified sulfate, nitrate, and ammonium ion absorption bands in ambient particles as well as bands indicating the presence of organics in diesel exhaust (C-H) and oxidized organics in irradiated hydrocarbon-NO, . mixtures. Since then, many studies using IR have been carried out and a variety of species identified, including COf , PO4-, and SiO A See Chapter 9.C.2 and Figs. 9.49, 9.50, and 9.51 for some typical FTIR spectra of atmospheric particles. 

Irradiation of films containing MB and the activators all resulted in polymerization, as judged by infrared spectroscopy and evidenced by formation of polymeric relief images after washout (65). Dye bleaching also resulted as shown in Fig. 7. 

A variety of examples of photochemically induced elimination of sulfur dioxide from sulfur heterocycles have been reported, with particular attention to cyclic sulfones. Thietan-3-one 1,1-dioxide (525), however, undergoes fragmentation on irradiation in acetonitrile to ketene (526) and to the sulfene (527), the latter identified by infrared spectroscopy and as the methanol... 

These conclusions were supported by transient absorption spectroscopy, which revealed signals corresponding to the formation of the diimine radical anion, with lifetimes in close agreement with the luminescence lifetimes. Time-resolved infrared spectroscopy of the acetylide C = C bonds provides further conclusive evidence for the MLCT assignment. Thus, in the ground state IR spectrum of 4, there are two v(C=C) bands at 2115 and 2124 cm-1, whilst the step-scan FTIR difference spectrum obtained 50 ns after irradiation at 355 nm reveals bleaching of the parent bands, and the formation... 

An intermediate epoxy ketene (39) from a-cleavage of 2,5-diphenyl-3(2H)-furanone (40) has been proposed by Padwa and co-workers to explain photoisomerization to 4,5-diphenyl-2(5H)-furanone (47)38. The epoxy ketene was not observed when the irradiation was monitored by infrared spectroscopy and was not trapped by methanol. The authors suggest that the intermediate may be formed with excess vibrational energy and as a result undergo very rapid intramolecular reaction. 

The temperature distribution is not only a function of radius, but also depends on the stellar luminosity, the disk geometry, and may depend on the accretion rate (see Table 8.1 and Section 3.3) for example, at a given radius irradiated flared disks will be warmer than flat disks. Naturally, hotter stars will heat their disks to higher temperatures at a given radius thus, mid-infrared spectroscopy probes different radii in different disks. 

The present chapter deals with the use of infrared spectroscopy in radiation chemistry. After an historical introduction and the presentation of the basic knowledge needed in infrared spectroscopy, we describe the major milestones of its implementation within that field. Section 3 describes the use of infrared spectroscopy in astrophysics. Starting in the 1980s, such studies aim at characterizing the sample s modifications after irradiation. Section 4 describes the implementation of infrared reflection-absorption spectroscopy (IR-RAS) and its use in understanding the radiation-induced surface chemistry. Section 5 is focused on the chemistry induced by swift heavy ions in polymers. Section 6 presents recent developments that enable us to perform... 

Far infrared spectroscopy has also revealed to be an efficient tool to study phase transitions. Low-frequency vibrations are different depending on whether water is crystalline (absorptions at 229 and 162 cm / or amorphous (broad absorption at 220 cm /. The authors have shown that crystalline water ice is converted into an amorphous phase under proton irradiation infrared spectroscopy enables quantifications of the rate of radiation-induced amorphization. The conversion... 

Infrared Spectroscopy A Tool to Characterize the Specificities of Swift Heavy Ions (SHI) Irradiations... 

In the Grand Accelerateur National dTons Lourds (GANIL, Caen, France) facility, ion beams are delivered in order to understand the specific characteristics of SHI-matter interactions. In particular, polymers are investigated. Infrared spectroscopy is a very powerful tool to characterize organic species in general and polymers in particular FT-IR spectra have been recorded in GANIL since 1994 in order to understand the specificities of SHI-polymers behavior. The first studies were ex situ measurements. Since 2003, SHI irradiations have been analyzed by means of in situ FT-IR spectroscopy. 

The experiments described above do not allow us to perform time-resolved measurements and to track the kinetics initiated by irradiation. While the time-resolved infrared spectroscopy was intensively and successfully developed with flash laser photolysis, time-resolved infrared spectroscopy was surprisingly not implemented in radiation chemistry until recently. 

The first coupling of a LINAC with infrared spectroscopy has been performed by Palmese et al. in order to study in situ kinetics of radiation-induced cationic polymerization of epoxy systems. The aim of the study is to understand the curing behavior of polymers under irradiation. A UV light source and an electron beam (10 MeV pulse width of the beam from 2.5 to 10 pm) are coupled to a portable near infrared (NIR) instrument. Briefly, a portable NIR spectrometer (Control Development Incorporated, South Bend, IN, USA) is used,... 

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