Application of Fusion Methods in Chemical Microscopy

Abstract

CHEMISTRYvisual portion become transparent when radiated with infrared (£). Microscope optics are transparent to near infrared as far as 2 n. The sensitivity of the eye falls off at about 7000 A. Ordinary infraredsensitive photographic materials have their peak sensitivity at about 8000 A. The infrared image tube (1P25, 14) used in World War II in the Sniperseope (11) has a peak sensitivity at about 8200 A.Figure 8. Molybdenite Interference figure shown with 1-mm. 0.85 IN.A. objective, is uniaxialAn infrared image is formed on a photoeathode, which gives off electrons proportional to the infrared radiation it receives. These electrons are accelerated in an increasing potential field and are brought to focus on a phosphor screen at the other end of the tube. A visual image, due to fluorescence of the excited phosphor, is present and can be viewed with a low power magnifier. This laboratory has adapted a 1P25 image tube for use over the eyepiece of a conventional microscope. The source of light used in this work is a carbon arc lamp fitted with a Corning No. 2540 filter to absorb the visual light and transmit the infrared portion of the spectrum. An example of this use of infrared (Figure 8) shows the uniaxial interference figure of molybdenite, a mineral opaque in visual light.

Effects of Solution Conditions on Polymorph Development in 2,4,6-Trinitrotoluene

“…TNT has a long history of researchers attempting to elucidate the complex details of its polymorphism. − As an example, McCrone, in his early work, famously concluded that TNT showed no evidence of polymorphism despite the fact that research into TNT’s crystal structure had been underway for over half a century. However, future work by McCrone and others (e.g., Grabar et al, Duke, Carper et al., and Golovina et al) laid the groundwork for the pioneering research conducted by the Sherwood group who thoroughly detailed the different crystal configurations and molecular conformations in each of TNT’s different polymorphic forms both experimentally and theoretically. − Moreover, there is significant interest in the fields of molecular engineering to be able to produce, modify, or discover different types of chemical polymorphs .…”

Chemical Microscopy

“…The general references under this heading include the first edition of the Kofler text, "Mikromethoden zur Kennzeichnung Organischer Stoffe und Stoffgemische" (204), a study comparing Kofler's thermal methods and fusion analysis ( 254), an introduction to fusion methods of organic compounds (238) and inorganic compounds (148), a general study of the Kofler methods ( 203), and an investigation on the microscopic identification of liquids by means of critical solution temperature measurement using sealed tubes with the Kofler hot stage (111). A second edition of the Kofler's book (204) will appear in late 1953 and an English translation of this edition in 1954.…”

Dimethylglyoxime: a restricted X-ray charge-density refinement

“…The conventional structure refinement All refinements to be described were carried out by a full-matrix least-squares method using the computer t The twin plane was reported as (001) by McCrone (1949). :~ Intensities were measured similarly for the weak reflection 002.…”