ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTUltrafast Electron Diffraction. 5. Experimental Time Resolution and ApplicationsMarcos Dantus, Scott B. Kim, J. Charles Williamson, Ahmed H. ZewailCite this: Phys. Chem. 1994, 98, 11, 2782–2796Publication Date (Print):March 1, 1994Publication History Published online1 May 2002Published inissue 1 March 1994https://pubs.acs.org/doi/10.1021/j100062a011https://doi.org/10.1021/j100062a011research-articleACS PublicationsRequest reuse permissionsArticle...

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTUltrafast Electron Diffraction. 4. Molecular Structures and Coherent DynamicsJ. Charles Williamson Ahmed H. ZewailCite this: J. Phys. Chem. 1994, 98, 11, 2766–2781Publication Date (Print):March 1, 1994Publication History Published online1 May 2002Published inissue 1 March 1994https://pubs.acs.org/doi/10.1021/j100062a010https://doi.org/10.1021/j100062a010research-articleACS PublicationsRequest reuse permissionsArticle...

A high-resolution flat-crystal spectrometer was used on the SuperEBIT electron beam ion trap to measure energies of $2{s}_{1/2}\ensuremath{-}2{p}_{3/2}$ transitions in lithiumlike through fluorinelike tungsten. These are strongly affected by energy shifts due quantum electrodynamics (QED). run at an $103.2\ifmmode\pm\else\textpm\fi{}0.5\text{ }\text{keV}$ and current 150 mA generate respective charge states; hydrogenlike aluminum neonlike krypton were as calibration elements. The spectra...

The experimental methodology for structural femtochemistry of reactions is considered. With the extension femtosecond transition-state spectroscopy to diffraction regime, it possible obtain in a general way trajectories chemical (change internuclear separations with time) on time scale. This method, considered here simple alkali halide dissociation, promises many applications more complex and conformational changes. Alignment scale experiments also discussed.

We describe a new undergraduate mechanics laboratory experiment that illustrates principles of linear and angular momentum conservation. Students observe is conserved in systems where the initial conditions involve only translational motion, yet final include rotational motion. To do this, students make digital video two-object collision on an air table. One object has asymmetric mass distribution gains kinetic energy as result collision. Using their video, create stroboscopic image two...

Excitation of molecular iodine vapor with a green (543.4 nm) helium−neon laser produces fluorescence spectrum that is well suited for the upper-level undergraduate physical chemistry laboratory. Application standard evaluation techniques to yields ground electronic-state parameters in good agreement literature values. The use provides advantages data collection, analysis, cost, and safety relative other I2 excitation sources.

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTTeaching the Rovibronic Spectroscopy of Molecular IodineJ. Charles Williamson View Author Information Department Chemistry, Willamette University, Salem, OR 97301Cite this: J. Chem. Educ. 2007, 84, 8, 1355Publication Date (Web):August 1, 2007Publication History Received3 August 2009Published online1 2007Published inissue 1 2007https://pubs.acs.org/doi/10.1021/ed084p1355https://doi.org/10.1021/ed084p1355research-articleACS PublicationsRequest reuse...

The lever rule applies to any two-component system existing in a state of two-phase equilibrium. Here, several classroom demonstrations are described help students understand liquid–liquid coexistence and the using set isobutyric acid + water dye samples ranging composition from dye. critical temperature partially miscible is just above room temperature, so can perceive general shape curve by watching progression phase separations take place over time as prewarmed single-phase allowed cool....

The synthetic-method determination of liquid-liquid coexistence curves using semiautomated light scattering instrumentation and stirred samples is based on identifying the curve transition temperatures (T(cx)) from sudden changes in turbidity associated with droplet formation. Here we use a thorough set such measurements to evaluate accuracy several different analysis methods reported literature for assigning T(cx). More than 20 each weakly opalescent isobutyric acid+water strongly...

Gas-phase molecular iodine laser-induced fluorescence (LIF) spectra were recorded out to 815 nm at 1 cm −1 resolution using green, yellow, and red helium-neon (HeNe) lasers as excitation sources. Nine previously unreported I 2 B ← X absorption transitions accessed by these identified, specific rovibronic transition assignments made for two hundred LIF peaks—more than sixty per laser. These peaks can be used calibrate the vacuum wavenumber coordinate of spectrometers better 0.1 accuracy. In...

In the vicinity of a critical point, impact substance's chemical identity is superseded by universal behavior for number physical properties, such as visible light scattering. this classroom demonstration, students observe single-phase mixture partially miscible isobutyric acid + water (IAW) liquid–liquid sample cools down to its temperature. Students see change from colorless and transparent, pale blue, white turbid. This optical called opalescence. No pressure control necessary...

A data set of 7,381 molecular iodine vapor rovibronic transitions between the X and B electronic states has been prepared for an advanced undergraduate spectroscopic analysis project. Students apply standard theoretical techniques to these determine values three X-state constants (B̃e″, ν̃e″, D̃e″) four B-state (B̃e′, ν̃e′, D̃e′, T̃e′). Morse potentials two may be calculated from seven constants.

Despite over a century of characterization efforts, liquid-liquid critical point compositions are difficult to identify with good accuracy. Reported values vary up 10% for even well-studied systems. Here, technique is presented high-precision determination the composition partially miscible binary liquid system. Ninety-degree laser light-scattering intensities from single-phase samples analyzed using an equation derived nonclassical power laws and pseudospinodal approximation. Results...

ADVERTISEMENT RETURN TO ISSUEPREVTech ReportNEXTInteractive Two-Component Phase DiagramsJ. Charles Williamson View Author Information Department of Chemistry, Willamette University, Salem, OR 97301Cite this: J. Chem. Educ. 2009, 86, 5, 653Publication Date (Web):May 1, 2009Publication History Received3 August 2009Published online1 May inissue 1 2009https://doi.org/10.1021/ed086p653RIGHTS & PERMISSIONSArticle Views3110Altmetric-Citations3LEARN ABOUT THESE METRICSArticle Views are the...

Critical opalescence turbidity masks the precise location of liquid−liquid coexistence curve temperatures (Tcx) in light scattering data collected from stirred samples using semiautomated instrumentation. A modified technique which a sample is fully equilibrated and then as function time with no stirring described. Tests on three systems (aniline + hexane, methanol cyclohexane, isobutyric acid water) showed that coalescence sedimentation unstirred two-phase causes distinct temporal changes...

We have expanded Stein's "Sweetness of Aspartame" laboratory project (Stein, P. J. Chem. Educ. 1997, 74, 1112, DOI: 10.1021/ed074p1112) to include extensive use statistical testing. Students test the significance a nonzero intercept in linear regression, bias comparison true value, and difference between replicate measurements two different samples. They also estimate error stemming from calibration curve explore pitfalls linearizing nonlinear data (e.g., unweighted Lineweaver–Burk plot)....

Under most conditions, a liquid mixture does not have long-range structural order and may be considered to homogeneous collection of molecules in random motion. However, if single-phase critical partially miscible liquid–liquid system is subjected small temperature jump into the two-phase region, then coherence across macroscopic distances can form liquid. The process called spinodal decomposition results because has made entire sample thermodynamically unstable. This fundamentally different...

Spectrometers configured with charge-coupled devices (CCD) or other array-based detectors require calibration to convert from the pixel coordinate a spectral coordinate. A CCD method well suited for Raman spectroscopy has been developed based on 514.5 nm Ar(+) laser-induced fluorescence (LIF) spectrum of room-temperature molecular iodine vapor. Over 360 primary and secondary I(2) LIF lines spanning 510-645 were identified as calibrant peaks using an instrumental resolution 1 cm(-1). Two...