b S Supporting Information T he physical chemistry laboratory course is an essential experience to the student wishing to pursue an advanced degree in chemistry or a career in a chemistry related field. A study in 2004 on physical chemistry curriculum points out that physical chemistry bridges physics, chemistry, and mathematics and develops complex critical-thinking skills required by scientists working on projects with interdisciplinary foci. 1 Physical chemistry now encompasses subareas too numerous to list and contributes to the study of almost all the other disciplines in chemistry. Today in a growing number of universities, however, the physical chemistry lab has been scaled back from the traditional two-semester period to just one semester. For example, in a recent informal survey of chemistry programs in the Southern Universities Group, approximately a quarter of the schools now only require one semester of physical chemistry lab to obtain a B.S. degree in chemistry. The loss of a whole semester has different roots, such as the desire to reduce the number of hours in a major or to make room for other new specialty courses such as environmental or forensic chemistry. The problem, therefore, arises in being able to provide students with enough lab experience to encompass the important areas of physical chemistry. Moore pointed out that it is extremely important to make sure the physical chemistry curriculum reflects what physical chemists really do. 2 With this in mind, in 1999, the University of Maryland integrated a program of physical and analytical techniques to investigate significantly more complex systems than those incorporated with one curriculum. 3 In 2004, Grand Valley State University sought to incorporate both computational and traditional physical chemistry laboratories in their curriculum, stating that the coupling of laboratories allows students to experience an experiment from a macroscopic, empirical point of view as well as an abstract, theoretical level that considers molecular-level events. 4 Combining multiple laboratory procedures into fewer multidimensional lab exercises allows students to be provided with opportunities encompassing multiple facets of physical chemistry in a constrained time frame. 5 Constructing a binary liquidÀvapor phase diagram is a classic physical chemistry experiment that is still taught in many chemistry departments and serves to illustrate an important physical concept. Here, we show that two other important concepts can be taught concurrently in this laboratory exercise, specifically molecular spectroscopy and quantum chemistry.The classic binary liquidÀvapor phase diagram experiment utilizes Raoult's law, which states that vapor pressure of an ideal solution is directly proportional to the mole fraction of each component. This law is a good approximation for a component only when its mole fraction is close to unity. Deviations, positive or negative, from Raoult's law give insight into the thermodynamic properties of the components involved. There have been...
A new device that combines vibration isolation and energy harvesting is modeled, simulated, and tested. The vibration isolating portion of the device uses post-buckled beams as its spring elements. Piezoelectric film is applied to the beams to harvest energy from their dynamic flexure. The entire device operates passively on applied base excitation and requires no external power or control system. The structural system is modeled using the elastica, and the structural response is applied as forcing on the electric circuit equation to predict the output voltage and the corresponding harvested power. The vibration isolation and energy harvesting performance is simulated across a large parameter space and the modeling approach is validated with experimental results. Experimental transmissibilities of 2% and harvested power levels of 0.36 μW are simultaneously demonstrated. Both theoretical and experimental data suggest that there is not necessarily a trade-off between vibration isolation and harvested power. That is, within the practical operational range of the device, improved vibration isolation will be accompanied by an increase in the harvested power as the forcing frequency is increased.
Storm water ponds are commonly employed to trap sediments, nutrients and other pollutants in non-point runoff. Aquatic macrophytes are thought to offer enhanced nutrient control via nutrient uptake and other processes. This study sampled and compared the phosphorus contents of water, sediment, and a dominant macrophyte, Stuckenia pectinata (Sago Pond Weed), in a storm water detention pond in the fall of 2013 and 2014. Phosphorus concentrations [ug P (g material)−1] were much higher in macrophyte tissues than in sediment and water, but the areal amounts of phosphorus (mg P m−2) bound in these three forms were ranked differently: sediment>>water>macrophyte, with macrophyte-bound P accounting for only <1–2% of total P in this pond. Macrophyte management may, therefore, have only marginal effectiveness in nutrient control by storm water detention ponds, although macrophytes support a variety of other ecosystem services.
Abstract. The study of the multiphoton ionization of methyl iodide has a long and storied history. Here, we revisit this topic and present spectra of each of the photoionization and photodissociation fragments (C + , CH + , CH + 2 , CH + 3 , CH 3 I + , and I + ) using a custom time-offlight mass spectrometer and a tunable dye laser over the excitation range of 550-740 nm (2.2-1.67 eV). The choice of this wavelength range allows for excitation through the A state and resonant ionization through higher energy levels using 4+1, 5+1, or 6+1 photons for excitation and ionization. Although the various fragments yield very similar spectra, fewer fragment ions are observed with increasing wavelength.
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