Extended abstract of a paper presented at Microscopy and Microanalysis 2006 in Chicago, Illinois, USA, July 30 – August 3, 2005

Extended abstract of a paper presented at Microscopy and Microanalysis 2005 in Honolulu, Hawaii, USA, July 31--August 4, 2005

Self-assembled structures are of increasing interest today due to the rapid progression of microand nanoscale engineering applications. In recent years much attention has been placed on understanding the formation and properties of monomolecular thin films, also known as selfassembled monolayers (SAMS), for use as corrosion inhibitors, lubricants, and adhesion promoters. Much of the advancement in this field has come from the unprecedented resolution of scanned probe microscopy, the scanning tunneling microscope (STM) and the atomic force microscope (AFM), invented in the mid to late 1980’s.

Cross-sectional scanning tunneling microscopy (STM) was combined with atomic force microscopy (AFM) over the same area to characterize a cross-sectioned GaN light emitting diode. Because GaN is typically grown on a non-native substrate and also forms a wurtzite crystal structure, a cryogenic cleaving technique was developed to generate smooth surfaces. The depletion region surrounding the p-n junction was clearly identified using STM. Furthermore, by imaging under multiple sample biases, distinctions between the n-doped and p-doped GaN could be made.

The process of self-assembled monolayer (SAM) formation by the spread coating of an octadecylphosphonic acid (OPA) solution onto a mica surface is investigated by atomic force microscopy, When concentrated solutions are employed, a novel mechanism of SAM formation is found: OPA multilayers, mostly bilayers, are initially deposited on the mica surface. As time passes, these large multilayers break apart and evolve into disorganized monolayers. Following a rapid evolution, such monolayers are found to transform into well-ordered OPA self-assembled monolayers.

Controlled scratches on octadecylphosphonic acid self-assembled monolayers were made using atomic force microscopy tips as indenters. Scratch morphological evolution was followed as a function of time, at room temperature, for samples prepared by drip coating and crystal melting methods. Self-healing, ranging from partial to complete, was observed on drip coated samples. However, no substantial healing was observed on crystal melted samples. Such different behaviour is discussed in terms of the scratching mechanism on both sample types.

In this Letter, we report on the use of atomic force microscopy to study the thermal stability of self-assembled monolayers (SAM) of octadecylphosphonic acid (OPA) grown on mica. The samples were sequentially annealed for 30 min steps at temperatures ranging from 50 to 200 degrees C. A major change in the SAM morphology takes place at temperatures similar to 95 degrees C, with the disappearance of the original flat-topped and partial-coverage SAM morphology. Concomitantly, the nucleation and growth of OPA precipitates in the investigated temperature range are observed. Two separate regimes are identified: initially, for temperatures up to similar to 110 degrees C, nucleation of OPA precipitates occurs, increasing their number density. Then, for temperatures above similar to 10 degrees C, growth of OPA precipitate size dominates, with the density of precipitates remaining approximately constant. A simple model used to fit the experimental data of both regimes enables an estimate of similar to 9 kcal/mol as the energy required for the disorganization (Ed) of OPA molecules on mica.

In this paper, we report on atomic force microscopy (AFM) investigation of a self-assembled monolayer (SAM) system-octadecylphosphonic acid (OPA) deposited on mica. With the deposition methods employed in this work, the SAM presents a partial coverage, i.e., the OPA covers only a fraction of the mica surface and, therefore, some bare mica regions are observed. Using standard intermittent contact AFM (IC-AFM) techniques (with medium to high oscillation damping), the topographic profile of this system clearly shows the flat SAM on top of the mica surface. However, when a small oscillation damping mode is employed, the topographic profile is inverted, i.e., the mica regions appear higher than the surrounding OPA layer. AFM experiments, carried out to assess the origin of this effect, yield strong evidences that it is related to the presence of a water contamination layer on the bare mica regions only. A semi-quantitative model is utilized to understand the experimental results.

Self-assembled monolayers (SAM) and multilayers of organic materials have been intensely studied in the past years, due to their numerous potential applications as, for example, lubricants, corrosioninhibitors and/or adhesion-promoters [1,2]. In this talk, we will present results of several studies carried out using Atomic Force Microscopy to investigate octadecylphosphonic acid (OPA) SAM deposited on mica. We have assessed various mechanisms of assembling, disassembling and reassembling the SAM on mica. The SAM deposition method employed in this work was drip coating using an OPA solution. We have used two different solvents, which exhibit very different OPA solubility, in this work: ethanol and trihydrofuran (THF). Regarding the assembling studies, we will show the formation of groups of OPA double-layers as the initial deposition stage (deposition time < 2 seconds) when using ethanol-based solutions. We will also show that annealing such samples at 60°C produces, favorably, OPA quadruple-layers, as shown in figures la and lb, respectively.

Abstract Self-assembled monolayers (SAM) and multilayers of organic materials have been intensely studied in the past years, due to their numerous potential applications as, for example, lubricants, corrosioninhibitors and/or adhesion-promoters [1,2]. Due to the reduced height of SAM, typically a couple of nanometers, the various Scanning Probe Microscopy (SPM) techniques, especially Scanning Tunneling Microscopy (STM) and Atomic Force Microscopy (AFM), have been the tools of choice in the morphological and structural study of those systems [1,2]. However, these SPM techniques have some limitations. One of them is the reduced scanning area, preventing the assessment of SAM coverage in large substrate areas, which is one of the key issues in studies of the potential applicability of SAM. Furthermore, due to their imaging principle, the SPM techniques are not suited to analyze SAM on substrates where the roughness is of the order of hundreds of nanometers or higher, impeding their application on most non-ideal (atomically flat) substrates.

Journal of School HealthVolume 64, Issue 4 p. 137-140 School (Health) Nursing in the Era of Health Care Reform: What is the Outlook? Marla E. Salmon, Marla E. Salmon Marla E. Salmon, ScD, RN, FAAN, Director, Division of Nursing, Bureau of Health Professions, Health Resources and Services Administration, U.S. Public Health Service, Room 9–35, 5600 Fishers Lane, Rockville. MD 20857.Search for more papers by this author Marla E. Salmon, Marla E. Salmon Marla E. Salmon, ScD, RN, FAAN, Director, Division of Nursing, Bureau of Health Professions, Health Resources and Services Administration, U.S. Public Health Service, Room 9–35, 5600 Fishers Lane, Rockville. MD 20857.Search for more papers by this author First published: April 1994 https://doi.org/10.1111/j.1746-1561.1994.tb03282.xCitations: 3 The views expressed in this paper are the author's and do not necessarily reflect those of the U.S. Dept. of Health and Human Services. AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onEmailFacebookTwitterLinkedInRedditWechat References 1 Health Security Act. Submitted by the President of the United States to the 103rd Congress; 1993. Google Scholar 2 Minutes. National Advisory Council on Nurse Education and Practice; May 1314, 1993 and December 9–10, 1993. Google Scholar 3 Lovato CY, Allensworth DD, Chan FA. School Health in America: An Assessment of State Policies to Protect and Improve the Health of Students. 5th ed. Kent, Ohio: American School Health Association; 1989. Google Scholar 4 Oda D.. The invisible nursing practice. Nurs Outlook. 1991; 39(1): 26–29. CASPubMedWeb of Science®Google Scholar 5 White MS. Construct for public health nursing. Nurs Outlook. 1982;NovDec: 527–530. CASGoogle Scholar 6 Lavin AT, Shapiro GR, Weill KS. Creating an agenda for school-based health promotion: A review of 25 selected reports. J Sch Health. 1992; 62(6): 212–228. 10.1111/j.1746-1561.1992.tb01231.x CASPubMedWeb of Science®Google Scholar 7 McGinnis JM, DeGraw C.. Healthy Schools 2000: Creating partnerships for the decade. J Sch Health. 1991; 61(7): 292–296. 10.1111/j.1746-1561.1991.tb07408.x CASPubMedWeb of Science®Google Scholar 8 Igoe JB, Giordano BP. Expanding School Health Services to Serve Families in the 21st Century. Washington, DC: American Nurses' Association; 1992. Google Scholar 9 Aiken L., Salmon ME. Keynote address on “National health care reform.” Presented at the National Nursing Summit hosted by the American Nurses' Association; August 1728, 1993; Chicago, Ill. Google Scholar 10 Oda DS. Nurse administrators' views of professional preparation in school nursing. J Sch Health. 1993; 63(5): 229–231. 10.1111/j.1746-1561.1993.tb06127.x CASPubMedWeb of Science®Google Scholar Citing Literature Volume64, Issue4April 1994Pages 137-140 ReferencesRelatedInformation

Public health nursing--the opportunity of a century. M E SalmonCopyRight https://doi.org/10.2105/AJPH.83.12.1674 Published Online: October 07, 2011