Praying Mantis

Hester, Jan, Mantis Creatures Join Alien Troops, UFO Magazine and Phenomena Report, 12(4) 25, July/August, 1997. (Discusses the praying mantis in alien abductions.)... 

Raman spectra were taken on a home built system, composed of Spectra-Physics 2020 series lasers, coupled with a Dilor XY-800 triple spectrometer and a Whight Instruments nitrogen cooled CCD. All samples were measured at room temperature in a backscattering configuration, with 514.53 nm Ar+ laser excitation. The laser power was tuned between 1 mW and 30 mW. UV-VIS diffuse reflectance spectra were taken on a Varian Cary 5 spectrophotometer, equipped with a specially designed Praying Mantis diffuse reflectance attachment of Harrick. 

The X-ray powder diffraction pattern was collected (Philips, PW 1840) with a Cu target and Ni filter (AcuKa = 0.15418 nm). The IR spectra were collected with a FTIR spectrometer (Bruker, Equinox 55) equipped with a diffuse reflectance sampling stage (Praying Mantis, Flarrick) utilizing the ambient chamber. The samples were analyzed by an UNI-SPECS ESCA system with a... 

The DRIFT spectra were recorded by a FTS 165 spectrometer of BIO-RAD Laboratories (Philadelphia, USA) using the praying-mantis-diffuse-reflection attachment. Unmodified metal or metal oxide particles were used as reference. The spectra were measured in Kubelka-Munk units collecting 32 scans. For data post processing the spectra were transformed in ASCII-files and processed in Origin 5.0. Smoothing was not done. 

An example of such an accessory that is marketed for application in the UV-vis regime is the Harrick Praying Mantis. A sketch and images are available at the Harrick webpage (Harrick, 2006) and have also been published by Weckhuysen (Weckhuysen and Schoonheydt, 1999, 2000 Weckhuysen, 2002,2003,2004) and other authors (Sojka et al., 2008). 

FIGURE 11 (A) MIR throughput of Harrick Praying Mantis DRP as provided by the... 

Reaction chambers fitting the Harrick Praying Mantis mirror optics are available commercially, and sketches or images are presented in the product description (Harrick, 2006), in the work of Weckhuysen and coworkers (Weckhuysen and Schoonheydt, 1999 Weckhuysen et al., 2000 Weckhuysen, 2002 Weckhuysen, 2003 Weckhuysen, 2004) and in a handbook article by Sojka et al. (2008). A low-pressure and a high-pressure version, suitable at pressures up to 202-303 kPa or 3.4 MPa (500 psi), are available they are characterized by a dome with either three flat, circular windows or a dome with a single quartz half-sphere shaped quartz block with a small (also half-sphere shaped) volume above the catalyst. Evacuation to pressures less than 1.33 x 10-6 hPa and a maximum temperature of 873 K (under vacuum) are specified. A low-temperature version is specified for 123-873 K and up to 202-303 kPa. In the low-pressure versions, there are several centimeters of beam path through the gas phase, so that gas phase contributions are more likely to be observed than in experiments with cells holding the sample directly at the window (this depends on the gas phase concentrations and molar absorption coefficients). 

An elaborate referencing procedure was suggested by Schulz-Ekloff et al. (1995), who could not fit their standard into the Praying Mantis reaction chamber. Groothaert et al. (2003) rescaled spectra to the most intense absorption bands because of instabilities of the fiber optics arrangement. 

DR Diffuse reflection geometry, TRc transmission geometry, IS Integrating sphere, PM Praying Mantis... 

If not otherwise specified, the experiments described in this section were performed with the Harrick Praying Mantis accessory and reaction cell. 

Harrick, "The Praying Mantis," product description, from www.harricksci.com, accessed Sept. 29, 2006. 

Diffuse reflection spectroscopy (UV-DRS). UV-Vis diffuse reflectance spectra were recorded in a Varian Cary 5 spectrophotometer (Harrick Scientific) with a diffuse reflectance accessory of Praying Mantis geometry. The samples were set in holds with 2 mm thickness. The spectra were recorded in the 200 nm and 800 nm range with a scanning speed of 1800 mm.min at room temperature against supports as reference. 

UV/VIS-DRS measurements were performed using a Cary 400 UV/VIS spectrometer (Varian) equipped with a diffuse reflectance accessory (praying mantis, Harrick). The reflectance spectra were converted into the Kubelka-Munk function F(R) which is proportional to the absorption coefficient for low values of F(R). Spectra were deconvoluted into Gaussian bands using the GRAMS/386 program (Galactic Industries Corporation). 

Infrared spectra (i.r.) Infrared spectra of the materials II and III were obtained with a BROKER IFS48 FT-IR spectrometer purged with nitrogen gas and using a mid band mercury cadmium telluride (MCI) detector. A HARRICK Praying Mantis diffuse reflectance attachment with two ellipsoidal mirrors collected the diffuse reflectance spectra. To avoid residual radiation bands all samples were diluted with KBr powder (Uvasol quality, E. Merck) so that the sample concentration was about 10 %. 

Figure 4.28. Optical diagram of Praying Mantis (Harrick Scientific Inc.) diffuse-reflectance accessory Mi, M2, M5, Me — plane mirrors Ms, M4 — 6 1 90° off-axis focusing and collecting ellipsoids. Sample is placed at position S. Adapted, by permission, from K. Moradi, C. Depecker, and J. Corset, Appl. Spectrosc. 48,1491 (1994), p. 1492, Fig. 2. Copyright 1994 Society for Applied Spectroscopy.

Solids can be measured in transmission or reflection (reflectance) modes. Both specular reflection and diffuse reflection are used. Diffuse reflection accessories include the Praying Mantis from Harrick Scientific Products, Inc., and a variety of integrating spheres available from most major instrument companies. Specular reflection is used for highly reflective materials diffuse reflectance for powders and rough surfaced solids. Materials characterization relies heavily on techniques like these. 

The Praying Mantis and its high-temperature reaction chamber have been used for studying temperature-induced wavelength changes in Thermal Liquid Crystal Paint, analyzing gas-soUd reactions such as heterogeneous catalysis, and routine analysis of powders and solids. Application notes can be found at www.harricksci.com. 

A.A. Walker, S. Weisman, T. Kameda, T.D. Sutherland, Natural templates for coiled-coD biomaterials from praying mantis egg cases. Biomacromolecules 13 (2012) 4264-4272. 

In the sample compartment, as much space as possible should be available to allow for thermostatically controlled sample holders or other equipment (Ulbricht globes, praying mantis devices, multicell holders, sippers). A secondary cooling circuit is useful to protect the optics and electronics from high temperature. Large sample compartments require well-thought-out, carefully calculated optical paths. Photochemical reactions can be followed directly in a spectrometer by special accessories [45]. 

Figure 53. Ray diagram of the Praying Mantis diffuse reflectance attachment...

Another method of measurement of diffuse reflectance does not require an integrating sphere. In this method, the sample beam is focused onto the sample by means of ellipsoidal or spherical mirrors and collected by another ellipsoidal mirror, at either 180 or 90° from the incident beam. This method has been used for many years in the infrared, since proposed by Fuller and Griffiths (1978, 1980). The advantage is very high collection efficiency and the ability to measure very small samples. Such geometry is known by a number of names, including biconical, Praying Mantis (a trade-... 

Fig. 14. Praying Mantis diffuse reflectance accessory. (Reprinted courtesy of Harrick Scientific Inc.)...

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