Time-Resolved Profiles in Modulated Polarization Spectroscopy
The absorption of a modulated light beam in which the state of the polarization is continuously variable is discussed. It is now possible to measure the average time-dependent profile for the polarization cycle of such a beam, and corresponding theoretical descriptions are needed in order to extract the information contained in it. This work generates such a description. Based on a semiclassical treatment of light/matter interactions, a three-parameter fit function is derived that permits the simultaneous extraction of absorbance, linear dichroism, and circular dischroism from the profile for various types of uniformly oriented, partially oriented, and isotropic materials and combinations of them. The theoretical expressions are used to analyze data for (+)-3-methylcyclopentanone, the results being (1) an increase of the S/N ratio, (2) the simultaneous generation of absorption and dichroism spectra of identical quality, and (3) a description of window adsorbates of the cyclopentanone material. The Jones p...
The Selective Digital Integrator: A New Device for Modulated Polarization Spectroscopy.
A new device, a selective digital integrator (SDI), for the acquisition o f modulated polarizaticm spectroscopy (MPS) signals is described. Special attention is given to the accurate measurement o f very small (AC component o f interest < lO'"’ x DC component), rapidly modulated (-50 kH z) signals at or below noise levels. Various data acquisition methcxis and problems associated with the collection o f modulated signals are discussed. The SDI solves most o f these problems and has the following advantages; it provides the average-time resolved profile o f a modulated signal; it eliminates errors if the modulation is not sinusoidal; it enables sqiarate m easurem aits o f the various phases o f the signal modulation cycle; it permits simultaneous measurement o f absorption, circular dichroism (CD) and linear dichroism (LD) spectra; it facilitates 3-D absorbance measuremraits; it has a wide gain-switching-free dynamic range (10 orders o f magnitude or more); it offers a constant S/N ratio mode o f operation; it eliminates the need for photomultiplier voltage feedback, and it has faster scanning speeds. The time-resolution, selectivity, wide dynamic range, and low-overhead on-the-fly data processing are useful for o ther modulated spectroscopy (MS) and non-MS experiments such as pulse height distribution and time-resolved pulse counting measurements. The advantages o f the MPS-SDI method are tested on the first Rydberg electronic transitions o f (+)-3-methylcyclopentanone. The experimental results validate the predicted SDI capabilities. However, they also point to two difficulties that had not been noted previously: the presence o f LD in a gaseous sample and a pressure-depaidence o f the relative peak heights o f the CD spectrum. Models for these anomaUes are proposed. The presence o f the oscillatory LD (but not an LD background) is explained with a sample cell model based on the observed polarization-depoidœt time-resolved profiles o f transmitted light intaisity. To obtain expressions for these intensities, a theoretical background, which provides a new approach to xvi R eproduced with perm ission of the copyright owner. Further reproduction prohibited without perm ission. the treatment o f light/matter interaction, is included as an Appaidix. To explain the second anomaly, present only at high optical daisities, a model based on the presoice o f scattered light is introduced and verified. The mode o f correction for the scattering problem is outlined.
Labour Law in a Globalising World
At the opening of the 21st century it is clear that increasing globalisation will remain one of the most important long term influences on the evolution of the international economy and international political structures. The controversial nature of globalisation is self-evident from the increasing intensity of antiglobalisation demonstrations at meetings of international bodies such as the World Trade Organisation. While the actual nature of globalisation, the direction in which it will take the world and the costs and benefits that will result are still contestable, it is clear that the main, and certainly the most effective, drivers are economic. Nations are primarily concerned to set in place structures that promote the free movement of capital including the freedom of multinational companies to locate and relocate around the world, and to promote free trade in goods and services. While non-economic values such as environmental protection and social and labour rights are not excluded from the debates setting these structures in place, they are largely marginal to it. One symbol of this marginalisation is that the ILO, unlike the World Bank, IMF and OECD, does not enjoy observer status at the WTO in spite of the rhetoric of concern for such rights from member states of the Organisation. As McCrudden and Davies explain,1 this exclusion is the result of a major and continuing division between developed and developing countries within the WTO that in the 1990s prevented agreement on any tangible measures in the Marrakesh agreements and that has continued to block subsequent progress. The stark divisions between these groups became even more apparent at the Singapore Ministerial meeting in 1996 when an invitation to the head of the ILO to speak was withdrawn. The only tangible result was a weak statement to the effect that members agreed that labour standards should be upheld but that this should be done through the ILO and not the WTO. The suspicion of developing countries that any link between trade and labour standards will lead to increased protectionism is almost certainly justified. Experience within the WTO to date provides little reason for developing countries to have any great faith in the undertakings of the developed world. Developing countries have seen the promises of movement toward freer trade that might benefit them fade into the distance while at the same time the undertakings they entered into are increasingly used to their disadvantage.2