First TERS Experiments

In September 2000, Hayazawa and coworkers reported the next study on apertureless SNOM using a silver-coated cantilever and a dye-coated silver film on a glass slide [137]. The dye was rhodamine 6g (Rh-6g). A 40-fold enhancement of Raman scattering was observed with a 4 8-nm laser excitation an enhancement of fluorescence was also noticed (see Fig. 10.16) [137]. The authors observed bleaching behavior for rhodamine 6g, but did not mention whether or not the bleaching rate was tip-enhanced. Instead, they pretreated this system with 20-min illumination until a stationary state was reached. 

In a further experiment, the authors scanned the metahzed cantilever within the laser focus, employing AFM contact mode. The recorded spectra are shown in Fig. 10.18 as a line image. This image was obtained with 0.5-mW laser illumination for 5 s per line scan. A lateral resolution of about 50 nm was reached in this experiment. 

2) By the net increase we mean the n-fold increase of the overall Raman signal in the 

Characteristic of many of the experiments described above and other TERS studies reported in the literature are (a) the use of an inverted microscope or illumination that is closely related to such a configuration, (b) the use of thick probe films, and (c) tips covered with metal grains. Each of these points indicates a non-optimal experimental condition for TERS. In fact, a configuration optimal for TERS requires (a) illumination with a strong polarization component parallel to the tip axis, (b) the possibility to use opaque, massive substrates, (c) an easy control of the adsorbate coverage, and (d) sharp, smooth tips with a 

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An Outlook is given in Section 10.5, sketching first of all the most recent TERS experiments and then possible developments in a number of directions. 

No reaction has been found with simple vinylpyrroles and TCNE. Nevertheless, there are examples of Diels-Alder reaction of some protoporphyrins with this dienophile. It was first reported [73JCS(P1)1424] that compound 184 reacted with TCNE in refluxing chloroform, giving the cycloadduct 185 in 56% yield. A later study reexamined the reaction and found more complicated chemistry (80JOC5196). In initial experiments, reactions of TCNE with protoporphyrin di-ter/-butyl ester were shown to give three major products, 186,187, and 188 but depending on the conditions of the reaction, time, solvent or amount of TCNE, the results were different. The authors also characterized compounds 189 and 190. 

J = 3/2, 5/2 and 7/2 levels of both fine-structure states. Also shown are the /l-doublet transitions observed, first by Dousmanis, Sanders and Townes [4], and subsequently by ter Meulen and Dymanus [165] andMeertsandDymanus [166]. The later studies [166] used molecular beam electric resonance methods which were described in chapter 8, and the most accurate laboratory measurements of transitions within the lowest rotational level were those of ter Meulen and Dymanus [165] using a beam maser spectrometer, also described in chapter 8. In the years following these field-free experiments, attention... 

Emulsion polymenzaticm without the use of an emulsifier may be achieved even with a monomer with v ter solubility as low as thet of styrene provided one uses an initiator such as potassium persulfate which introduces ionic end groups into the polymer that can stabilize the polymer latex particles produced electrostatically. Emulsifier free emulsion polymerization is advantageous when the object is to obtain a well-characterized model colloid for use in experiments on colloidal stability, etc. Then it is usually desirable that the surfaces of the colloidal particles be clean. When an emulsifier is used in the iH eparation, its removal (e.g., by dialysis) is generally so incomplete that it is simpler to avoid its use in the first place. However, emulsifier-free latexes are necessarily dilute and consequently of little interest for commercial applications. 

The risk assessment is conducted in two tiers. In the first tier, fixed conservative default input parameters given in the EU Guidance Document SANCO 4145/2000 are used for the ETE-calculation [1], The first tier is meant to be a screening process, selecting uncritical products and uses that will pass the process fast and easily. However, experience shows that actually about 75% of the first tier risk assessments do not pass one of the TER-trigger values. When a product does not pass the Tier 1, it enters the higher tier or refined risk assessment. In the Tier 2, a full justification is needed for all assumptions which differ from the Tier 1 default values. 

Cyclones have been used to remove particulates from gas streams since the middle of the 19th century (Rietema and Verver, 1961). Early researchers (Rosin et al., 1932 Alexander, 1949 Stairmand, 1951 Ter Linden, 1949 linoya, 1953 Lapple, 1951 van Tongren, 1936) conducted the first experiments designed to understand the operation of this mechanically simple but operationally complex device. Many of these experiments (Ter Linden, 1949 Lapple, 1951 Stairmand, 1951, etc.) resulted in cyclone designs based on relative cyclone dimensions. More recently, Zenz (1975) developed an empirical cyclone design procedure that has achieved popular acceptance in the United States. 

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