Nanometriskaalan mittausten jäljitettävyys, atomivoimamikroskoopit nanometrologiassa

Reliability of measurement is a crucial element of both research and industry. Metrological traceability to the SI unit metre guarantees commensurate units, also at nanometre range. In this thesis, a traceability chain is established for nanometre scale measurements. Measurement instruments and methods were developed for accurate measurements, calibration of instruments and transfer standards, and uncertainty estimations. A metrological atomic force microscope (MAFM) was developed and characterized. The MAFM can be used in the calibration of transfer standards and in accurate AFM measurements. Calibration methods for commercial AFMs were developed. A laser diffractometer was also developed for accurate calibration of 1-D and 2-D gratings with a standard uncertainty of several tens of picometres. Laser interferometric position measurement with a calibrated vacuum wavelength is directly traceable to the realization of the metre if measuring full interferometer fringes, but there is small nonlinearity in sub-fringe measurements. Therefore, in sub-nanometre measurements the nonlinearity of the interferometer needs to be corrected. A method for this correction was developed. Laser diffraction measurement is a very accurate method for characterization of grating pitch. One of the main uncertainty sources is the uncertainty of the measured diffraction angle. Therefore, a method for calibration of the rotary table of the laser diffraction setup was developed. The method can be used also in the realization of angle scale. Methods for transfer standard calibration were developed for both pitch and step height calibration by MAFM. An acoustic method was developed for compensation of the refractive index of air in interferometric measurements. Sub-nanometre uncertainty can be reached with this method. Characterization of instruments, validation of methods and uncertainty estimations are a crucial part of traceability. Therefore, uncertainty estimates based on the characterization of the instruments are given for all measurements in this thesis. Comparisons between laboratories are the best way to ensure commensurate measurements. International comparison results between national metrology institutes for pitch and step height transfer standards are listed.Mittausten luotettavuus on tärkeää sekä tutkimuksessa että teollisuudessa. Mittausten metrologinen jäljitettävyys SI-yksiköiden määritelmiin takaa yhdenmukaiset yksiköt. Tässä väitöskirjassa luotiin jäljitettävyysketju nanometritason mittauksille. Helpoiten jäljitettävyys saadaan käyttämällä kalibroituja kalibrointinäytteitä. Väitöskirjassa kehitettiin kalibrointinäytteiden kalibrointiin sopivia laitteita ja menetelmiä. Väitöskirjassa kehitettyjä metrologista atomivoimamikroskooppia (MAFM) ja laser diffraktometria voidaan käyttää nanometritason mittauksiin käytettävien mittanormaalien kalibrointiin. Molemmissa mittauksissa jäljitettävyys metrin määritelmään saadaan laserin tyhjiöaallonpituuden kautta. Mittausepävarmuuden tunteminen on oleellinen osa jäljitettävyysketjua, joten kaikille väitöskirjan mittauksille on tehty epävarmuuslaskelmat. Tarkimmat pituusmittaukset tehdään laserinterferometrilla. Siinä käytetään hyväksi laserin tyhjiöaallonpituutta, joka pystytään määrittämään pienellä epävarmuudella. Menetelmä on tarkka, jos mitataan täysiä aallonpituuksia. Sitä lyhyemmillä etäisyyksillä mittauksessa on pieni epälineaarisuus, jonka korjaamiseksi kehitettiin yksinkertainen menetelmä. Interferometrisissa mittauksissa pitää tuntea ilman taitekerroin. Taitekerroin riippuu lämpötilasta, kosteudesta ja paineesta. Paine ja kosteus on helppo mitata riittävän tarkasti perinteisillä menetelmillä, mutta lämpötilan muutokset voivat olla nopeita ja niiden mittaaminen vaikeaa. Väitöskirjassa jatkokehitettiin menetelmää ilman lämpötilan ja taitekertoimen määrittämiseksi äänennopeuden avulla laser-säteen kulkureitillä. Kansainväliset vertailumittaukset ovat hyvä tapa varmistaa mittayksiköiden yhdenmukaisuus. Väitöskirjassa esitetään kansallisten metrologialaitosten välisiä vertailumittaustuloksia urasyvyys ja hilanormaaleille. Näissä vertailuissa on käytetty väitöskirjatyössä kehitettyjä laitteita ja menetelmiä. Tulokset ovat hyvin yhteensopivia vertailun referenssiarvon kanssa

DNA origami structures as calibration standards for nanometrology

Peer reviewe

A técnica do questionário na pesquisa educacional

O presente trabalho almeja discutir o emprego do questionário enquanto técnica de coleta de dados, recorrentemente empregada nas pesquisas que envolvem o levantamento de uma grande quantidade de dados, como também o seu emprego nas pesquisas de cunho qualitativo. Aqui, decidiu-se pelo recorte espacial de estudo dessa técnica, especificamente, orientado para trabalhos de conclusão de curso de graduandos dos cursos tecnológicos de instituição de ensino superior privada. Este trabalho pretende demonstrar a importância da pesquisa na construção do conhecimento e destacar a urgência de se socializar e divulgar o conhecimento científico entre os discentes de nível superior como forma de conhecer, participar e intervir na realidade. Soma-se a isso, a partir da identificação percebida pelos autores quando da orientação de trabalhos de conclusão de curso, a necessidade de apontar a relevância da escolha adequada da técnica de coleta de dados para o alcance dos resultados esperados. Pretende, ainda, mostrar que o questionário é uma técnica bastante viável e pertinente para ser empregada quando se trata de problemas cujos objetos de pesquisa correspondem a questões de cunho empírico, envolvendo opinião, percepção, posicionamento e preferências dos pesquisados. Neste sentido, busca-se destacar a forma pela qual são construídas as perguntas do questionário, atentando-se para o conteúdo, número e ordem das questões, uma vez que as perguntas são as responsáveis pelo alcance das respostas ao desenvolvimento dos trabalhos. Este estudo fundamenta-se nos autores que tratam da temática, tendo como principais fontes de pesquisa os autores: GIL (1999), RICHARDSON (1999), MARCONE (1999), MALHOTRA (2006), MATALLO (2000), GIL (1996) e RIBEIRO (2008)

Atomic force microscope adhesion measurements and atomistic molecular dynamics simulations at different humidities

Due to their operation principle atomic force microscopes (AFMs) are sensitive to all factors affecting the detected force between the probe and the sample. Relative humidity is an important and often neglected-both in experiments and simulations-factor in the interaction force between AFM probe and sample in air. This paper describes the humidity control system designed and built for the interferometrically traceable metrology AFM (IT-MAFM) at VTT MIKES. The humidity control is based on circulating the air of the AFM enclosure via dryer and humidifier paths with adjustable flow and mixing ratio of dry and humid air. The design humidity range of the system is 20-60 % rh. Force-distance adhesion studies at humidity levels between 25 % rh and 53 % rh are presented and compared to an atomistic molecular dynamics (MD) simulation. The uncertainty level of the thermal noise method implementation used for force constant calibration of the AFM cantilevers is 10 %, being the dominant component of the interaction force measurement uncertainty. Comparing the simulation and the experiment, the primary uncertainties are related to the nominally 7 nm radius and shape of measurement probe apex, possible wear and contamination, and the atomistic simulation technique details. The interaction forces are of the same order of magnitude in simulation and measurement (5 nN). An elongation of a few nanometres of the water meniscus between probe tip and sample, before its rupture, is seen in simulation upon retraction of the tip in higher humidity. This behaviour is also supported by the presented experimental measurement data but the data is insufficient to conclusively verify the quantitative meniscus elongation.Peer reviewe

Middleborns disadvantaged? testing birth-order effects on fitness in pre-industrial finns

Parental investment is a limited resource for which offspring compete in order to increase their own survival and reproductive success. However, parents might be selected to influence the outcome of sibling competition through differential investment. While evidence for this is widespread in egg-laying species, whether or not this may also be the case in viviparous species is more difficult to determine. We use pre-industrial Finns as our model system and an equal investment model as our null hypothesis, which predicts that (all else being equal) middleborns should be disadvantaged through competition. We found no overall evidence to suggest that middleborns in a family are disadvantaged in terms of their survival, age at first reproduction or lifetime reproductive success. However, when considering birth-order only among same-sexed siblings, first-, middle-and lastborn sons significantly differed in the number of offspring they were able to rear to adulthood, although there was no similar effect among females. Middleborn sons appeared to produce significantly less offspring than first-or lastborn sons, but they did not significantly differ from lastborn sons in the number of offspring reared to adulthood. Our results thus show that taking sex differences into account is important when modelling birth-order effects. We found clear evidence of firstborn sons being advantaged over other sons in the family, and over firstborn daughters. Therefore, our results suggest that parents invest differentially in their offspring in order to both preferentially favour particular offspring or reduce offspring inequalities arising from sibling competition