logging in or signing up Forensic Glass Analysis Dionigi Download Post to : URL : Related Presentations : Share Add to Flag Embed Email Send to Blogs and Networks Add to Channel Uploaded from authorPOINTLite Insert YouTube videos in PowerPont slides with aS Desktop Copy embed code: (To copy code, click on the text box) Embed: URL: Thumbnail: WordPress Embed Customize Embed The presentation is successfully added In Your Favorites. Views: 2725 Category: Education License: All Rights Reserved Like it (5) Dislike it (1) Added: January 09, 2008 This Presentation is Public Favorites: 4 Presentation Description No description available. Comments Posting comment... By: maryann68 (8 month(s) ago) Very complete and good organised presentation Saving..... Post Reply Close Saving..... Edit Comment Close By: jouma (16 month(s) ago) very nice presentation Saving..... Post Reply Close Saving..... Edit Comment Close Premium member Presentation Transcript Forensic Glass Analysis: Forensic Glass Analysis Continuing Education Program in Forensic Science April 5, 2004Glass: Glass “An inorganic product of fusion which has cooled to a rigid condition without crystallizing” Does not have a specific m.p. Softens over a temperature rangeGlass Components: Glass Components Formers – Network Formation SiO2, B2O3, P2O5, GeO2, V2O5, As2O3, Sb2O5 Fluxes – Softeners Na2O, K2O, LiO, Al2O3, B2O3, Cs2O Stabilizers – Provide Chemical Resistance CaO, MgO, Al2O3, PbO, SrO, BaO, ZnO, ZrO Major Types of Glass: Major Types of Glass Soda lime silicate glass SiO2 + Na2O / K2O + CaO / Al2O3 / MgO Flat glass, container glass, electric light bulbs Borosilicate glass > 5% B2O3 (in place of Na2O) Lab glassware, thermometers, cookware, sealed-beam headlightsSlide5: Aluminosilicate glass Higher percentage of aluminum Useful at higher temperatures than borosilicate Aluminoborosilicate – 50:50 Al/B Labware, cookware, and glass fibers Lead alkali silicate (leaded glass) Up to 80% PbO Low softening temp, high refractive index “Crystal” tableware, Major Forensic Glass Sources: Major Forensic Glass Sources Flat Glass – Soda lime silicate Drawing, Rolling, or Floating Tempered: Rapid Cooling Adds Strength Dices when broken Automotive windows & security windows Float Glass floresces when excited at 254 nm.Slide7: Coated: Surface modification Mirrors Laminated: Sandwiched around plastic Automotive windshields Headlights: Sometimes borosilicate Light bulbs: Soda lime glass Heat absorbing/ UV filtering Tinted Photochromic (Light Sensitive) EyeglassesSlide8: Container Glass Lower magnesium, higher sodium Clear vs. greenish (window) Glass Fibers Fiberglass insulation Alumino-borosilicate Binder (red or yellow) to hold fibers in bundles Is It Glass?: Is It Glass? Isotropic vs. Anisotropic Glass: Isotropic Remains dark when rotated under crossed polarizers Crystalline solids and plastics: Anisotropic Change brightness when rotated under crossed polarizers Hardness: Pin test Solubility (distinguish salt)Comparison of Physical Characteristics: Comparison of Physical Characteristics Color (Microscopy) Flatness (Microscopy, Interferometry) Thickness Full thickness required 0.79 – 6.2 mm Fluorescence – Float Glass 254 nm, note colorPhysical Properties: Physical Properties Density Sink-Float Method CHBr3, C2H2Br4, Sodium Polytungstate Density Range 2.465-2.540 g/cm3 Slide12: Index of Refraction: symbol n Measured by Na-D line 589nm at 20°C Other wavelengths Hydrogen-C 656.3 nm Hydrogen-F 486.1 nm θi θr Slide13: Dispersion (V) – Change in Refractive Index with wavelength Chemical Composition – Inductively Coupled Plasma (ICP) SEM with EDX Neutron Activation Analysis X-Ray Fluorescence Determining Refractive Index: Determining Refractive Index Liquid Immersion When glass and liquid have same refractive index, particle will be (nearly) invisible Becke Line = Halo around particle Moves to medium of higher index of refraction when microscope is defocused by moving the stage down. Becke LineSlide15: Method of Continuous Variation Glass RI: 1.470 – 1.560 Immersion Liquids: Silicone Oils Organic Compounds Cyclohexanone 1.448 m-xylene 1.494 Methylsalicylate 1.522 Benzaldehyde 1.544 Benzyl benzoate 1.568 You do not have the permission to view this presentation. In order to view it, please contact the author of the presentation.
Forensic Glass Analysis Dionigi Download Post to : URL : Related Presentations : Share Add to Flag Embed Email Send to Blogs and Networks Add to Channel Uploaded from authorPOINTLite Insert YouTube videos in PowerPont slides with aS Desktop Copy embed code: (To copy code, click on the text box) Embed: URL: Thumbnail: WordPress Embed Customize Embed The presentation is successfully added In Your Favorites. Views: 2725 Category: Education License: All Rights Reserved Like it (5) Dislike it (1) Added: January 09, 2008 This Presentation is Public Favorites: 4 Presentation Description No description available. Comments Posting comment... By: maryann68 (8 month(s) ago) Very complete and good organised presentation Saving..... Post Reply Close Saving..... Edit Comment Close By: jouma (16 month(s) ago) very nice presentation Saving..... Post Reply Close Saving..... Edit Comment Close Premium member Presentation Transcript Forensic Glass Analysis: Forensic Glass Analysis Continuing Education Program in Forensic Science April 5, 2004Glass: Glass “An inorganic product of fusion which has cooled to a rigid condition without crystallizing” Does not have a specific m.p. Softens over a temperature rangeGlass Components: Glass Components Formers – Network Formation SiO2, B2O3, P2O5, GeO2, V2O5, As2O3, Sb2O5 Fluxes – Softeners Na2O, K2O, LiO, Al2O3, B2O3, Cs2O Stabilizers – Provide Chemical Resistance CaO, MgO, Al2O3, PbO, SrO, BaO, ZnO, ZrO Major Types of Glass: Major Types of Glass Soda lime silicate glass SiO2 + Na2O / K2O + CaO / Al2O3 / MgO Flat glass, container glass, electric light bulbs Borosilicate glass > 5% B2O3 (in place of Na2O) Lab glassware, thermometers, cookware, sealed-beam headlightsSlide5: Aluminosilicate glass Higher percentage of aluminum Useful at higher temperatures than borosilicate Aluminoborosilicate – 50:50 Al/B Labware, cookware, and glass fibers Lead alkali silicate (leaded glass) Up to 80% PbO Low softening temp, high refractive index “Crystal” tableware, Major Forensic Glass Sources: Major Forensic Glass Sources Flat Glass – Soda lime silicate Drawing, Rolling, or Floating Tempered: Rapid Cooling Adds Strength Dices when broken Automotive windows & security windows Float Glass floresces when excited at 254 nm.Slide7: Coated: Surface modification Mirrors Laminated: Sandwiched around plastic Automotive windshields Headlights: Sometimes borosilicate Light bulbs: Soda lime glass Heat absorbing/ UV filtering Tinted Photochromic (Light Sensitive) EyeglassesSlide8: Container Glass Lower magnesium, higher sodium Clear vs. greenish (window) Glass Fibers Fiberglass insulation Alumino-borosilicate Binder (red or yellow) to hold fibers in bundles Is It Glass?: Is It Glass? Isotropic vs. Anisotropic Glass: Isotropic Remains dark when rotated under crossed polarizers Crystalline solids and plastics: Anisotropic Change brightness when rotated under crossed polarizers Hardness: Pin test Solubility (distinguish salt)Comparison of Physical Characteristics: Comparison of Physical Characteristics Color (Microscopy) Flatness (Microscopy, Interferometry) Thickness Full thickness required 0.79 – 6.2 mm Fluorescence – Float Glass 254 nm, note colorPhysical Properties: Physical Properties Density Sink-Float Method CHBr3, C2H2Br4, Sodium Polytungstate Density Range 2.465-2.540 g/cm3 Slide12: Index of Refraction: symbol n Measured by Na-D line 589nm at 20°C Other wavelengths Hydrogen-C 656.3 nm Hydrogen-F 486.1 nm θi θr Slide13: Dispersion (V) – Change in Refractive Index with wavelength Chemical Composition – Inductively Coupled Plasma (ICP) SEM with EDX Neutron Activation Analysis X-Ray Fluorescence Determining Refractive Index: Determining Refractive Index Liquid Immersion When glass and liquid have same refractive index, particle will be (nearly) invisible Becke Line = Halo around particle Moves to medium of higher index of refraction when microscope is defocused by moving the stage down. Becke LineSlide15: Method of Continuous Variation Glass RI: 1.470 – 1.560 Immersion Liquids: Silicone Oils Organic Compounds Cyclohexanone 1.448 m-xylene 1.494 Methylsalicylate 1.522 Benzaldehyde 1.544 Benzyl benzoate 1.568