Average size and alignment is just the beginning of the information that SAXS can provide. By analyzing different portions of the angular response, one can also obtain surface areas, fibril thickness and fractal dimension, a measure of how solid the object is. A very important feature of SAXS is the ability to resolve periodic structures, such as crystalline or liquid crystalline structures.

Equipment Selection and Design. We propose to purchase a Bruker SAXS instrument, consisting of two subsystems: 1) SAXS system; and 2) detector. The SAXS subsystem features maximum accessible Bragg spacings of 99 nm, evacuated beam path with vacuum system, optical rail for pinhole and X-ray alignment, beamstop, sample changer, sample-to-detector distance of 65.0 cm. The two-dimensional detector subsystem uses a multiwire proportional chamber and position decoding circuit to detect X-rays and present a digital image of the scattering pattern. The user can select from 512 x 512 or 1024 x 1024 pixels. Calibration tools, frame buffer and analysis software are provided. The SAXS instrument will become part of a very versatile X-ray scattering system, purchased partly with departmental funds given to Prof. Thomas. The full system will include a large six-circle goniometer with point detector to efficiently scan the reciprocal space. The area detector from the Bruker SAXS can be removed and remounted on the goniometer to rapidly find interesting spots for very detailed study. Normally, it will reside near zero angle--a normal SAXS configuration.

SAXS systems are not simple "plug and pray" devices. The students will be actively involved in building sample ovens and configuring the SAXS to two X-ray sources. One will be the 18 kW rotating anode generator Professor Thomas is purchasing for use in Choppin Hall (Chemistry building). The other will be the synchrotron light source at CAMD. These two sources present different characteristics. The rotating anode generator is comparatively compact, always available, lower in intensity but very stable. It is suitable for investigations of samples at thermodynamic equilibrium, provided the electron contrast between the macromolecule and its surroundings is good. CAMD, located a few miles off campus, occupies a large separate building, will be available about 25% of the time, is very bright but produces a sawtooth intensity profile as electrons are injected into the storage ring and then slowly lost. It is suitable for rapidly evolving systems, samples that must be confined in strong or thick containers, and systems with low electron contrast.

Sample Research Project 1. Elongational Flow-induced Fiber Alignment. Professor Negulescu proposes to study the molecular alignment in fibers. The student for this project can originate from either the Chemistry or Human Ecology Departments, and would work in close concert with a student directed by Thomas. Negulescu is already studying elongational viscosity of polymer melts using an advanced capillary extrusion rheometer fitted with semi-hyperbolic dies that define a purely elongational flow (no shear) field at constant elongational strain rate. Enthalpy changes can be determined in conjunction with the shear viscosity. Our preliminary investigation of melt relaxation and the associated first-decay time constants of metallocene-catalyzed polyolefins, over a wide range of molecular weights and branching orientation, suggest that with increasing strain rate, the molecular field of the melt gains orientation. The enthalpy changes associated with the orientation development were at least ten times lower than the heat of fusion of crystalline polymers as determined by differential scanning calorimetry(DSC). Despite their power, rheology and DSC are indirect methods incapable of confirming enhanced alignment. They can only suggest it. In the first phase of research (i.e., after the equipment is working) the area detector will be used with the rotating anode generator to test for alignment of the fibers. In the second phase, dynamic experiments using the intense synchrotron source will be attempted. The just-extruded fiber will be measured as a function of position from the exit to determine the relaxation rate of the alignment, if indeed there is alignment. These results could be used as preliminary data to gain time on an even more intense synchrotron source or small angle neutron scattering device at a national laboratory, a terrific opportunity for the student. The greater penetrating power may enable study directly inside the elongational flow, but preliminary evidence from our SAXS would surely be required. A SAXS device at CAMD will be a gateway to national facilities.

Sample Research Project 2. Soft matter. Professor Thomas is interested in the interplay between chiral interactions and molecular conformations on the macroscopic shapes attained by lipid multilayer membranes. A particularly striking example of these interactions is provided by the vesicles composed of the synthetic diacetylenic phospholipid 1,2-bis(10,12-tricosadiynoyl)-sn-glycero-3-phosphocholine, which produce stable multilamellar vesicles with an astonishing cylindrical morphology upon cooling. These hollow vesicles, or "tubules", are typically tens of microns in length, just under one micron in diameter and appear to be composed of a helically wound phospholipid multilayer ribbon.(Thomas, 1998, 1999) The tubules' highly unusual cylindrical symmetry make them items of compelling scientific interest; furthermore, their dimensions and hollowness endow them with great potential in "nano-technology," biological, and encapsulation applications. Thomas' group is also designing and synthesizing new analogs of tubule-forming molecules with the long-term goals of understanding their formation processes and of optimizing their dimensions for their wide variety of potential applications. SAXS will be a key ingredient to elucidating the structure of tubules and other systems. Recent SAXS data (acquired elsewhere) established a predicted chiral liquid crystal phase in which there is a regular array of twist grain boundaries separating layered smectic-A slabs and was earlier used to study layer constriction. (Rappaport, 1995) Thomas' group is also studying the structural effects of applied electric and magnetic fields on oriented liquid crystal samples; this is a potential source of interaction with Russo, who studies polymer diffusion in liquid crystals.

Other IGERT Research Projects. The gels to be synthesized by Spivak and McCarley will benefit from correlation length and surface area measurements. Small changes in protein conformation are of great interest to Licata; these are inaccessible to visible light scattering. Core-shell composite particles can be analyzed for shell thickness. The organized hairy rod networks described above require SAXS study. Changes in those networks due to backbone conformation transitions require synchrotron SAXS. The biophysical faculty are often interested in quite small changes in quite small proteins. At present, these are measured by a battery of hydrodynamic methods. It is not possible to discern changes in shape or size from changes in hydration because the well-defined radius of gyration is not available without SAXS. The fiber thickness and mass/unit length of amyloid protofibrils can be determined.

Industrial and Other Applications. Investigators in the Materials Technology Center would use the SAXS in areas such as zeolite and catalyst characterization, ceramic powder synthesis, motor oil additives, polymer blends. Some industrial users exist, and more will be identified by our outreach programs. Likely targets include fine mineral additives in motor oil, branched polymers and copolymer rubbers. In areas where we do have the equipment, offers to measure something relevant at LSU are almost always accepted, providing valuable contacts while helping industrial partners. Invitations to visit and use the machines "hands-on" are also often accepted.

Need. There is no publicly available SAXS in Louisiana, even though the state accounts for about 25% of the national U.S. chemical output. We know of one SAXS apparatus at an industrial site, but it is only available on a limited basis and span as much reciprocal space as the requested apparatus will. The absence of SAXS is the single most glaring equipment deficiency on the LSU campus. Travel to national centers is possible--even beneficial--but only for the few who can. To integrate SAXS into the curriculum and raise the consciousness of the faculty about what it can do requires a local instrument.

Capability of Investigators. The arrival of Assistant Professor Britt Thomas in August 1999 brings extensive rotating anode and synchrotron source X-ray scattering experience to the LSU Chemistry Department. Of particular relevance is Thomas' experience with unusual samples, such as liquid crystals in freely-suspended films or infused into silica aerogels, or under applied electric fields. He has also worked with membrane-bound protein systems, organic Langmuir films on water, and liquid metal substrates. He has studied kinetic probes of self-assembling systems. These systems present a widely different set of temperature, humidity and vacuum. Each also has its own sample translation and X-ray beam orientation requirements. Consequently, it is routine to radically modify an existing sample oven for the experiment at hand, or to construct a new one altogether to meet the requirements of the system. Russo began in graduate school with an impossible (for the time) SAXS project, which eventually launched his interest in visible light scattering. Japanese researchers working on a very powerful synchrotron just succeeded (Izumi, 1998) on a very similar project. This is testimony to the importance of an intense source. Currently, Russo's needs for SAXS are met via collaborations.(Yu, 1997; Russo, 1999; Jamil, 1994) He looks forward to being able to expose his students (not literally) to the power of X-ray scattering. Negulescu has traveled to Stanford Synchrotron Radiation Laboratory to study difficult annealing problems in molten liquid crystals. With care, preliminary evidence for a smectic ordering of a rather large liquid crystal former was identified. Such large periodicities are important for materials fabrication. The proposed LSU SAXS would enable a kinetics study to see how rapidly the structures build. DiTusa uses scattering in his studies of the low-temperature physics of strongly correlated materials (doped semiconductors, itinerant magnets, magnetoresistive materials). He will be a resource for technique. We hope to team-teach a special topics course in general scattering methods, under the auspices of LSU's emerging Materials Technology Center.

Implementation. Professor Thomas will assume primary responsibility for the construction of the device, with input from diTusa (Physics; he has a deep understanding of scattering, but is not an IGERT participant since his interests are in fundamental physics of nonpolymeric materials) and Russo (Chemistry). Thomas will also be assisted by off-campus participant Beaucage (Materials Engineering, U. Cincinnati) who has built several SAXS devices and used many in a polymer context. The CAMD staff devoted to this project (2 person-years) will assist with the synchrotron interface and safety issues. The SAXS construction project will be advertised early in the program. We are seeking one or more students who wish to learn drafting, machining, optics (X-ray and visible, used for alignment), and computer programming in modern control languages such as Visual Basic, Visual C or LabView. At the same time, the student must plug into a bonafide research objective; equipment building is a means not an end. We hope a team of 2-3 students will work intensively on the main construction. Others will have to fabricate special adapters (e.g., ovens, flow cells, humidity chambers) as an integral part of their research. We would like each Craftsperson to leave having built or designed something, whether for the SAXS or another device. The SAXS team will travel to other synchrotron sites (Stanford, Brookhaven, APS) with a consistent set of LSU-relevant samples (fibers, liquid crystals, liposomes, aerocrystals, dilute protein and polymer solutions) to make a useful comparison and introduce students to the national laboratory scene. They will also study a rotating anode device constructed by a former Russo student at Yale. An excellent opportunity exists in the lab of Professor Yachin Cohen at the Technion in Israel; closer to home, a student might spend some time with participant Greg Beaucage. These investigations can take place while the equipment is on order. The students will return knowing what to expect (demand) when vendor representatives arrive to assist with the early phases of setup (on the rotating anode generator). After experience on the rotating anode generator, construction at CAMD can begin.

Number of IGERT apprentices to be recruited and probable home departments: See "Implementation" above.

Consistency with the Macromolecular Education, Research & Training theme: SAXS is a classic, powerful method for elucidating polymer structures. Construction of a device at LSU will require skills appropriate to a macromolecular craftsperson, such as drafting and design, soldering, programming, light machining and at least an appreciation for vacuum science, X-ray optics and electronics.

How do students benefit from the team-oriented research, beyond what would be available to them from either advisor separately? LSU students do learn about scattering, but lab experience is limited to visible light. One could hardly find similarities between a SAXS device and a light scattering machine, even though the two share a common theoretical basis. In light scattering, we have been able to successfully integrate lab and lecture, as demonstrated in an accepted article to Journal of Chemical Education (Poche', in press). We are eager to do same for SAXS, a related but very different animal.

Interdisciplinary strengths of the team project: The above descriptions only hint at the projects that will gather around the new SAXS as students of MS-III/IV teach other faculty its uses, ranging from dilute biopolymer solutions to fiber processing. How interdisciplinary is magnetic resonance to chemistry and medicine? That's how interdisciplinary SAXS is to macromolecular science.

Thomas and Russo will directly work with new apprentices, initially at remote sites to introduce them to the various design schemes, safety considerations and sample measurement strategies. Other interested faculty may also make these trips, provided only that they have samples to measure.

Jamil, T., P. S. Russo, I. Negulescu, W. H. Daly, D. W. Schaefer and G. Beaucage, Light Scattering from Random Coils Dispersed in a Solution of Rodlike Polymers, Macromolecules, 27, 171-178 (1994).

Poche',D.S., P. S. Russo, B. Fong, E. Temyanko and H. Ricks, Teaching Static Light Scattering for the Characterization of Polymers, J. Chem. Ed., in press (editor: John W. Moore, Editor: tel: 504-549-2893, ms #1998-0600)

Russo, P.S., M. Baylis, Z. Bu, W. Stryjewski, G. Doucet, E. Temyanko and D. Tipton, Self Diffusion of a Semiflexible Polymer Measured Across the Lyotropic Liquid Crystalline Phase Boundary, J. Chem. Phys., 111(4), 1746-1752 (1999).

Thomas, B.N; Lindemann, C.M.; Clark, N.A., Left- and Right-Handed Helical Tubule Intermediates from a Pure Chiral Phospholipid, Phys. Rev. E, 1999, 59, 3040-3047.

Rappaport, A.G.; Williams, P.A.; Thomas, B.N.; Clark, N.A.; Blanca Ros, M.; Walba, D.M. ,X-Ray Observation of Electroclinic Layer Constriction and Rearrangement in a Chiral Smectic-A Liquid Crystal, Applied Physics Letters 1995, 67, 362.

Thomas, B.N.; Corcoran, R.C.; Cotant, C.L.; Lindemann, C.M.; Kirsch, J.E.; Persichini, P.J., Phosphonate Lipid Tubules I, J. Amer. Chem. Soc. 1998, 120, 12178-12186.

 Average size and alignment is just the beginning of the information that SAXS can provide. By analyzing different portions of the angular response, one can also obtain surface areas, fibril thickness and fractal dimension, a measure of how solid the object is. A very important feature of SAXS is the ability to resolve periodic structures, such as crystalline or liquid crystalline structures.

Equipment Selection and Design. We propose to purchase a Bruker SAXS instrument, consisting of two subsystems: 1) SAXS system; and 2) detector. The SAXS subsystem features maximum accessible Bragg spacings of 99 nm, evacuated beam path with vacuum system, optical rail for pinhole and X-ray alignment, beamstop, sample changer, sample-to-detector distance of 65.0 cm. The two-dimensional detector subsystem uses a multiwire proportional chamber and position decoding circuit to detect X-rays and present a digital image of the scattering pattern. The user can select from 512 x 512 or 1024 x 1024 pixels. Calibration tools, frame buffer and analysis software are provided. The SAXS instrument will become part of a very versatile X-ray scattering system, purchased partly with departmental funds given to Prof. Thomas. The full system will include a large six-circle goniometer with point detector to efficiently scan the reciprocal space. The area detector from the Bruker SAXS can be removed and remounted on the goniometer to rapidly find interesting spots for very detailed study. Normally, it will reside near zero angle--a normal SAXS configuration.

SAXS systems are not simple "plug and pray" devices. The students will be actively involved in building sample ovens and configuring the SAXS to two X-ray sources. One will be the 18 kW rotating anode generator Professor Thomas is purchasing for use in Choppin Hall (Chemistry building). The other will be the synchrotron light source at CAMD. These two sources present different characteristics. The rotating anode generator is comparatively compact, always available, lower in intensity but very stable. It is suitable for investigations of samples at thermodynamic equilibrium, provided the electron contrast between the macromolecule and its surroundings is good. CAMD, located a few miles off campus, occupies a large separate building, will be available about 25% of the time, is very bright but produces a sawtooth intensity profile as electrons are injected into the storage ring and then slowly lost. It is suitable for rapidly evolving systems, samples that must be confined in strong or thick containers, and systems with low electron contrast.

Sample Research Project 1. Elongational Flow-induced Fiber Alignment. Professor Negulescu proposes to study the molecular alignment in fibers. The student for this project can originate from either the Chemistry or Human Ecology Departments, and would work in close concert with a student directed by Thomas. Negulescu is already studying elongational viscosity of polymer melts using an advanced capillary extrusion rheometer fitted with semi-hyperbolic dies that define a purely elongational flow (no shear) field at constant elongational strain rate. Enthalpy changes can be determined in conjunction with the shear viscosity. Our preliminary investigation of melt relaxation and the associated first-decay time constants of metallocene-catalyzed polyolefins, over a wide range of molecular weights and branching orientation, suggest that with increasing strain rate, the molecular field of the melt gains orientation. The enthalpy changes associated with the orientation development were at least ten times lower than the heat of fusion of crystalline polymers as determined by differential scanning calorimetry(DSC). Despite their power, rheology and DSC are indirect methods incapable of confirming enhanced alignment. They can only suggest it. In the first phase of research (i.e., after the equipment is working) the area detector will be used with the rotating anode generator to test for alignment of the fibers. In the second phase, dynamic experiments using the intense synchrotron source will be attempted. The just-extruded fiber will be measured as a function of position from the exit to determine the relaxation rate of the alignment, if indeed there is alignment. These results could be used as preliminary data to gain time on an even more intense synchrotron source or small angle neutron scattering device at a national laboratory, a terrific opportunity for the student. The greater penetrating power may enable study directly inside the elongational flow, but preliminary evidence from our SAXS would surely be required. A SAXS device at CAMD will be a gateway to national facilities.

Sample Research Project 2. Soft matter. Professor Thomas is interested in the interplay between chiral interactions and molecular conformations on the macroscopic shapes attained by lipid multilayer membranes. A particularly striking example of these interactions is provided by the vesicles composed of the synthetic diacetylenic phospholipid 1,2-bis(10,12-tricosadiynoyl)-sn-glycero-3-phosphocholine, which produce stable multilamellar vesicles with an astonishing cylindrical morphology upon cooling. These hollow vesicles, or "tubules", are typically tens of microns in length, just under one micron in diameter and appear to be composed of a helically wound phospholipid multilayer ribbon.(Thomas, 1998, 1999) The tubules' highly unusual cylindrical symmetry make them items of compelling scientific interest; furthermore, their dimensions and hollowness endow them with great potential in "nano-technology," biological, and encapsulation applications. Thomas' group is also designing and synthesizing new analogs of tubule-forming molecules with the long-term goals of understanding their formation processes and of optimizing their dimensions for their wide variety of potential applications. SAXS will be a key ingredient to elucidating the structure of tubules and other systems. Recent SAXS data (acquired elsewhere) established a predicted chiral liquid crystal phase in which there is a regular array of twist grain boundaries separating layered smectic-A slabs and was earlier used to study layer constriction. (Rappaport, 1995) Thomas' group is also studying the structural effects of applied electric and magnetic fields on oriented liquid crystal samples; this is a potential source of interaction with Russo, who studies polymer diffusion in liquid crystals.

Other IGERT Research Projects. The gels to be synthesized by Spivak and McCarley will benefit from correlation length and surface area measurements. Small changes in protein conformation are of great interest to Licata; these are inaccessible to visible light scattering. Core-shell composite particles can be analyzed for shell thickness. The organized hairy rod networks described above require SAXS study. Changes in those networks due to backbone conformation transitions require synchrotron SAXS. The biophysical faculty are often interested in quite small changes in quite small proteins. At present, these are measured by a battery of hydrodynamic methods. It is not possible to discern changes in shape or size from changes in hydration because the well-defined radius of gyration is not available without SAXS. The fiber thickness and mass/unit length of amyloid protofibrils can be determined.

Industrial and Other Applications. Investigators in the Materials Technology Center would use the SAXS in areas such as zeolite and catalyst characterization, ceramic powder synthesis, motor oil additives, polymer blends. Some industrial users exist, and more will be identified by our outreach programs. Likely targets include fine mineral additives in motor oil, branched polymers and copolymer rubbers. In areas where we do have the equipment, offers to measure something relevant at LSU are almost always accepted, providing valuable contacts while helping industrial partners. Invitations to visit and use the machines "hands-on" are also often accepted.

Need. There is no publicly available SAXS in Louisiana, even though the state accounts for about 25% of the national U.S. chemical output. We know of one SAXS apparatus at an industrial site, but it is only available on a limited basis and span as much reciprocal space as the requested apparatus will. The absence of SAXS is the single most glaring equipment deficiency on the LSU campus. Travel to national centers is possible--even beneficial--but only for the few who can. To integrate SAXS into the curriculum and raise the consciousness of the faculty about what it can do requires a local instrument.

Capability of Investigators. The arrival of Assistant Professor Britt Thomas in August 1999 brings extensive rotating anode and synchrotron source X-ray scattering experience to the LSU Chemistry Department. Of particular relevance is Thomas' experience with unusual samples, such as liquid crystals in freely-suspended films or infused into silica aerogels, or under applied electric fields. He has also worked with membrane-bound protein systems, organic Langmuir films on water, and liquid metal substrates. He has studied kinetic probes of self-assembling systems. These systems present a widely different set of temperature, humidity and vacuum. Each also has its own sample translation and X-ray beam orientation requirements. Consequently, it is routine to radically modify an existing sample oven for the experiment at hand, or to construct a new one altogether to meet the requirements of the system. Russo began in graduate school with an impossible (for the time) SAXS project, which eventually launched his interest in visible light scattering. Japanese researchers working on a very powerful synchrotron just succeeded (Izumi, 1998) on a very similar project. This is testimony to the importance of an intense source. Currently, Russo's needs for SAXS are met via collaborations.(Yu, 1997; Russo, 1999; Jamil, 1994) He looks forward to being able to expose his students (not literally) to the power of X-ray scattering. Negulescu has traveled to Stanford Synchrotron Radiation Laboratory to study difficult annealing problems in molten liquid crystals. With care, preliminary evidence for a smectic ordering of a rather large liquid crystal former was identified. Such large periodicities are important for materials fabrication. The proposed LSU SAXS would enable a kinetics study to see how rapidly the structures build. DiTusa uses scattering in his studies of the low-temperature physics of strongly correlated materials (doped semiconductors, itinerant magnets, magnetoresistive materials). He will be a resource for technique. We hope to team-teach a special topics course in general scattering methods, under the auspices of LSU's emerging Materials Technology Center.

Implementation. Professor Thomas will assume primary responsibility for the construction of the device, with input from diTusa (Physics; he has a deep understanding of scattering, but is not an IGERT participant since his interests are in fundamental physics of nonpolymeric materials) and Russo (Chemistry). Thomas will also be assisted by off-campus participant Beaucage (Materials Engineering, U. Cincinnati) who has built several SAXS devices and used many in a polymer context. The CAMD staff devoted to this project (2 person-years) will assist with the synchrotron interface and safety issues. The SAXS construction project will be advertised early in the program. We are seeking one or more students who wish to learn drafting, machining, optics (X-ray and visible, used for alignment), and computer programming in modern control languages such as Visual Basic, Visual C or LabView. At the same time, the student must plug into a bonafide research objective; equipment building is a means not an end. We hope a team of 2-3 students will work intensively on the main construction. Others will have to fabricate special adapters (e.g., ovens, flow cells, humidity chambers) as an integral part of their research. We would like each Craftsperson to leave having built or designed something, whether for the SAXS or another device. The SAXS team will travel to other synchrotron sites (Stanford, Brookhaven, APS) with a consistent set of LSU-relevant samples (fibers, liquid crystals, liposomes, aerocrystals, dilute protein and polymer solutions) to make a useful comparison and introduce students to the national laboratory scene. They will also study a rotating anode device constructed by a former Russo student at Yale. An excellent opportunity exists in the lab of Professor Yachin Cohen at the Technion in Israel; closer to home, a student might spend some time with participant Greg Beaucage. These investigations can take place while the equipment is on order. The students will return knowing what to expect (demand) when vendor representatives arrive to assist with the early phases of setup (on the rotating anode generator). After experience on the rotating anode generator, construction at CAMD can begin.