Molecular beams with a tunable velocity

The merging of molecular beam methods with those of accelerator physics has yielded new tools to manipulate the motion of molecules. Over the last few years, decelerators, lenses, bunchers, traps, and storage rings for neutral molecules have been demonstrated. Molecular beams with a tunable velocity and with a tunable width of the velocity distribution can now be produced, and are expected to become a valuable tool in a variety of physical chemistry and chemical physics experiments. Here we present a compact molecular beam machine, capable of producing 3D spatially focused packets of state-selected accelerated or decelerated molecules.     

Accelerators and lasers as sources of pulsed excitation present status

The past quarter of a century has seen considerable improvement in time resolution for pulse radiolysis and laser photolysis experiments, made possible by advanced excitation sources. To document the present status, three installations for pulse radiolysis are discussed: a picosecond linac (Tokyo), a nanosecond Van de Graaff (Delft), and a high current accelerator (ód). Also indicated are future experimental possibilities, in particular the use of a high current photoemission electron gun. Available lasers for excitation with nanosecond pulses are summarized and a picosecond facility which permits optical and conductivity observations with subnanosecond time resolution is described.     

FAIR@Germany

The proposed international Facility for Antiproton and Ion Research (FAIR) at GSI-Darmstadt, will be a source of exotic radionuclidic beam and is expected to be operational in 2016. The facility will deliver 2 GeV/u to 45 GeV/u beam covering the entire range of the periodic table with the intensities three orders of magnitude higher than that available anywhere in the world today. This facility will serve all areas of fundamental sciences including nuclear physics, physics at extreme density conditions like neutron stars, plasma and laser physics, hadron physics and applied areas in chemistry, biology and material sciences. In this article, we discuss briefly the FAIR facility, with special emphasis on Indian participation.     

Linear electron accelerator for radioanalytical studies at Tohoku University

We introduce the status of the 300-MeV electron linear accelerator used for radioanalytical studies at Tohoku University. In the accelerator facility, several scientific programs for producing radioactivities and use have been performed in several fields, such as photon activation analysis, study of nuclear phenomena influenced by chemical nature, radioisotope production for trace elements, radiation chemistry and irradiation effects by electrons and photons, radioisotope labeling and its mechanism. We show the outlook of the facility, instrumental developments of a beam-course, an irradiation system and several measurement devices. Further, we display a radioanalytical topic in practice, evaluation of trace amount of potassium in high-purity reagent of Gd₂O₃ by photon activation analysis.     

The autonomy of chemistry: old and new problems

The autonomy of chemistry and the legitimacy of the philosophy of chemistry are usually discussed in the context of the issue of reduction of chemistry to physics, and defended making use of the failure of reductionistic claims. Until quite recent times a rather widespread viewpoint was, however, that the failure of reductionistic claims concerns actually epistemological aspect of reduction only, but the ontological reduction of chemistry to physics cannot be denied. The new problems of the autonomy of chemistry in the context of reductionism seem to be ontological and metaphysical. In the present paper it is argued that there is no need for some kind of metaphysical-ontological underpinning for rejection of the secondary positions of chemistry and philosophy of chemistry with respect to physics and philosophy of physics. The issue can be elucidated in terms of the philosophy of science accepting practical realism (also known by other names).     

Mössbauer spectroscopy in China

Mössbauer spectroscopy is a dynamic field with applications ranging from physics to biology. This paper gives a review of Mössbauer spectroscopy activities carried out by different groups in China. About thirty groups are distributed all over China for both fundamental and practical aspects. In-beam Mössbauer setup was established at HIRAC accelerator in Lanzhou, and the nuclear scattering facility has already been planned at Shanghai Synchrotron Radiation Light Source. In this review, some recent developments and achievements are discussed, as examples: (1) Brownian motion in anisotropic media, (2) applications to archaeology, and (3) molecule-based magnetic materials.     

Another scientific practice separating chemistry from physics: thought experiments

Thought experiments in the history of science display a striking asymmetry between chemistry and physics, namely that chemistry seems to lack well-known examples, whereas physics presents many famous examples. This asymmetry, I argue, is not independent data concerning the chemistry/physics distinction. The laws of chemistry such as the periodic table are incurably special, in that they make testable predictions only for a very restricted range of physical conditions in the universe which are necessarily conditioned by the contingences of chemical investigation. The argument depends on how ‚thought experiment’ is construed. Here, several recent accounts of thought experiments are surveyed to help formulate what I call ‚crucial’ thought experiments. These have a historical role in helping to judge between hypotheses in physics, but are not helpful in chemistry past or present.     

Teaching the integrated and modern perspectives of analytical chemistry

The present situation of analytical chemistry teaching within a chemistry curriculum is exemplified by the reformed chemistry curriculum in Germany. This approach is contrasted with teaching analytical chemistry within a novel curriculum in natural sciences termed 'applied science'. The latter curriculum ensures a superior education in chemistry, physics, biology, mathematics and information science, thus gaining an integrated perspective of analytical chemistry.     

Teaching the integrated and modern perspectives of analytical chemistry

The present situation of analytical chemistry teaching within a chemistry curriculum is exemplified by the reformed chemistry curriculum in Germany. This approach is contrasted with teaching analytical chemistry within a novel curriculum in natural sciences termed ‘applied science’. The latter curriculum ensures a superior education in chemistry, physics, biology, mathematics and information science, thus gaining an integrated perspective of analytical chemistry.     

Measurements of the photonuclear neutron yield of 15 MV medical linear accelerator

High energy medical linear accelerators (>10 MV) are increasingly used in radiotherapy. At such high photon energies neutron production via photonuclear reactions in the heavy elements which compose the linac head is inevitable. Neutrons from linacs can contribute to an additional dose to staff, patients and the general public. Our intention is two-fold; to provide shielding against the neutron contamination and to establish the depthdose curve of thermal neutrons within human tissue, with an aim to utilise linacs in boron neuron capture therapy (BNCT). In our studies neutron measurements were undertaken, with a Varian Clinac 2100C/D linear accelerator operating at 15 MV nominal energy, by irradiating 18 cm thick 30×30 cm² block of tissue equivalent material. Measurements were taken using indium and aluminum activation foil at the centre of the block. Our results show that by leaving the linac jaws open neutron production is increased compared to the case when these are shut, for one minute exposure at 400MU. In this work we present a comparison between our results and existing literature and attempt to explore some sharp contrasts.     

Enhancing Instruction in Upper Division Chemistry at California State University Fullerton

At California State University Fullerton the Departments of Chemistry and Biochemistry and Physics have jointly established an active learning instructional computer facility where students explore models and data in the upper division chemistry and physics curricula. This facility is also a component of the larger W.M. Keck Foundation Center for Molecular Structure (CMolS), a core research and education center where faculty and students throughout the California State University system have the opportunity for joint research and teaching activities directed at the determination and critical analysis of molecular structures. An array of Silicon Graphics workstations and a server housed in an electronic classroom provides a networking medium linking students and faculty across our curricula to resources and courses with common themes, but traditionally segregated. Through team teaching and utilization of resources and expertise across subdisciplines and disciplines, we are creating a learning pathway that coherently exposes our students in chemistry and biochemistry to more sophisticated problems and exploration. Computers provide visual reinforcement and inerpretation for concepts and principles that students may have difficulty understanding and that cannot be treated easily or well by the problem-solving methodology. Our students have responded enthusiastically to the electronic classroom, and introduction of chemical computation into the curriculum has had a positive pedagogical impact.     

Plasma electroradiolysis of aqueous solutions

Electroradiolysis of aqueous solutions, a process that is induced by the action of glow discharge on an electrolytic cathode, is considered. The results of investigation of systems of this type are summarized. The set of phenomena at the discharge plasma/electrolyte-cathode interface is treated in terms of radiation chemistry, plasma chemistry, emission electronics, and gas discharge physics. A new area of research, electroradiation chemistry of water and aqueous solutions, is presented.     

Linking chemistry with physics: arguments and counterarguments

The many-faced relationship between chemistry and physics is one of the most discussed topics in the philosophy of chemistry. In his recent book Reducing Chemistry to Physics. Limits, Models, Consequences, Hinne Hettema (Reducing chemistry to physics. Limits, models, consequences, Rijksuniversiteit Groningen, Groningen, 2012) conceives this relationship as a reduction link, and devotes his work to defend this position on the basis of a “naturalized” concept of reduction. In the present paper I critically review three kinds of issues stemming from Hettema’s argumentation: philosophical, scientific and methodological.     

Reflections About Mathematical Chemistry

A personal account is presented for the present status of mathematical chemistry, with emphasis on non-numerical applications. These use mainly graph-theoretical concepts. Most computational chemical applications involve quantum chemistry and are therefore largely reducible to physics, while discrete mathematical applications often do not. A survey is provided for opinions and definitions of mathematical chemistry, and then for journals, books and book series, as well as symposia of mathematical chemistry.     

Future perspectives of radiation chemistry

Future perspectives of radiation chemistry are discussed by the analysis of the related information in detail as obtained from our recent surveys of publications and scientific meetings in radiation chemistry and its neighboring research fields, giving some examples, and are summarized as follows. (1) Traditionally important core-parts of radiation chemistry should be activated more. The corresponding research programs are listed in detail. (2) Research fields of physics, chemistry, biology, medicine, and technology in radiation research should interact more among them with each other. (3) Basic research of radiation chemistry should interact more with its applied research. (4) Interface research fields with radiation chemistry should be produced more with mutually common viewpoints and research interests between the two. Interfaces are not only applied research but also basic one.     

Look Better: Single Atoms in Chemistry and Single Atoms in Physics

Fostering fruitful collaboration between chemistry and physics scholars, the analysis of the differences in the practical approach to single atoms in chemistry and in physics affords a number of conceptual outcomes pointing to a more balanced and useful relationship between chemistry and physics.     

A state of the art electron beam sterilization facility : An integrated system

The design of an electron beam sterilization facility requires the integration of the accelerator, product handling system and shielding. The size and power of the accelerator as well as the characteristics of the product handling system are determined by the type and volume of products to be sterilized. The system controls must track the product as it moves from the non sterile area through the electron beam to the sterile area. The system must not only monitor identification, position, orientation etc., but also isolate those products which for any reason may not have been properly sterilized. The shielding design is a function of the requirements for the accelerator and product handling system with an overriding concern for worker safety.

This paper discusses a state of the art electron beam sterilization facility designed to follow guidelines for electron beam sterilization published by the Association for the Advancement of Medical Instrumentation (AAMI).     

The Ontological Autonomy Of The Chemical World

In the problem of the relationship between chemistry and physics, many authors take for granted the ontological reduction of the chemical world to the world of physics. The autonomy of chemistry is usually defended on the basis of the failure of epistemological reduction: not all chemical concepts and laws can be derived from the theoretical framework of physics. The main aim of this paper is to argue that this line of argumentation is not strong enough for eliminate the idea of a hierarchical dependence of chemistry with respect to physics. The rejection of the secondary position of chemistry and the defense of the legitimacy of the philosophy of chemistry require a radically different philosophical perspective that denies not only epistemological reduction but also ontological reduction. Only on the basis of a philosophically grounded ontological pluralism it is possible to accept the ontological autonomy of the chemical world and, with this, to reverse the traditional idea of the ‘superiority’ of physics in the context of natural sciences.     

What History Tells Us about the Distinct Nature of Chemistry

Attention to the history of chemistry can help us recognise the characteristics of chemistry that have helped to maintain it as a separate scientific discipline with a unique identity. Three such features are highlighted in this paper. First, chemistry has maintained a distinct type of theoretical thinking, independent from that of physics even in the era of quantum chemistry. Second, chemical research has always been shaped by its ineliminable practical relevance and usefulness. Third, the lived experience of chemistry, spanning the laboratory, the classroom and everyday life, is distinctive in its multidimensional sensuousness. Furthermore, I argue that the combination of these three features makes chemistry an exemplary science.