Wyniki wyszukiwania - Biblioteka Nauki

1

Precision spectroscopy of cold strontium atoms, towards optical atomic clock

100%

Bober M. , Zachorowski J. , Gawlik W. , Morzyński P. , Zawada M. , Lisak D. , Cygan A. , Bielska K. , Piwiński M. , Trawiński R. , Ciuryło R. , Ozimek F. , Radzewicz C.

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2012

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tom Vol. 60, nr 4

707-710

EN

This report concerns the experiment of precision spectroscopy of cold strontium atoms in the Polish National Laboratory of Atomic, Molecular and Optical Physics in Toruń. The system is composed of a Zeeman slower and magneto-optical traps (at 461 nm and 689 nm), a frequency comb, and a narrow-band laser locked to an ultra-stable optical cavity. All parts of the experiment are prepared and the first measurements of the absolute frequency of the 1S0-3P1, 689 nm optical transition in 88Sr atoms are performed.

2

Cavity ring down spectroscopy : detection of trace amounts of substance

100%

Stacewicz T. , Wojtas J. , Bielecki Z. , Nowakowski M. , Mikołajczyk J. , Mędrzycki R. , Rutecka B.

Opto-Electronics Review

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2012

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tom Vol. 20, No. 1

53-60

EN

We describe several applications of cavity ring-down spectroscopy (CRDS) for trace matter detection. NO₂ sensor was constructed in our team using this technique and blue-violet lasers (395–440 nm). Its sensitivity is better than single ppb. CRDS at 627 nm was used for detection of NO₃. Successful monitoring of N₂O in air requires high precision mid-infrared spectroscopy. These sensors might be used for atmospheric purity monitoring as well as for explosives detection. Here, the spectroscopy on sharp vibronic molecular resonances is performed. Therefore the single mode lasers which can be tuned to selected molecular lines are used. Similarly, the spectroscopy at 936 nm was used for sensitive water vapour detection. The opportunity of construction of H₂O sensor reaching the sensitivity about 10 ppb is also discussed.

3

Detection of disease markers in human breath with laser absorption spectroscopy

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Stacewicz T. , Bielecki Z. , Wojtas J. , Magryta P. , Mikolajczyk J. , Szabra D.

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tom Vol. 24, No. 2

82--94

EN

Number of trace compounds (called biomarkers), which occur in human breath, provide an information about individual feature of the body, as well as on the state of its health. In this paper we present the results of experiments about detection of certain biomarkers using laser absorption spectroscopy methods of high sensitivity. For NO, OCS, C₂H₆, NH₃, CH₄, CO and CO(CH₃)₂ an analysis of the absorption spectra was performed. The influence of interferents contained in exhaled air was considered. Optimal wavelengths of the detection were found and the solutions of the sensors, as well as the obtained results were presented. For majority of the compounds mentioned above the detection limits applicable for medicine were achieved. The experiments showed that the selected optoelectronic techniques can be applied for screening devices providing early diseases detection.

4

Application of high-accuracy time-resolved laser spectroscopy to the study of diffusion-controlled triplet-triplet annihilation

100%

Borowicz P. , Nickel B.

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tom Vol. 12, No. 3

325-332

EN

The kinetics of the diffusion-controlled triplet-triplet annihilation of anthracene was investigated with the time-resolved laser spectroscopy. The analysis of the decays of delayed fluorescence with the standard Smoluchowski model leads to an artificial dependence of the annihilation radius from the delay (starting point of evaluation). The intuitive-empirical modification of the so-called short-time term in Smoluchowski equation (based on the treatment of the triplet-triplet annihilation as a non-Fickian diffusion) is proposed. A brief comparison is presented between standard Smoluchowski and modified models for anthracene. The limits of the approximation used are discussed and the way of further progress is suggested.

5

The 61Π u state of Na2 molecule

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Grochola A. , Kubkowska M. K. , Jastrzębski W. , Kowalczyk P.

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2006

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tom Vol. 36, nr 4

s. 469--473

EN

Excitation spectra of sodium dimer were analysed within the range 34200–36400 cm–1. The experiment was done using polarisation labelling spectroscopy technique. In the spectral region under investigation we found several vibrational progressions belonging to a single band system having the ground state of Na2 as the lower state. The upper state was of 1Π u symmetry as indicated by the presence of Q lines in the spectrum and basing on theoretical calculations it was identified as the 61Π u (3s+4f ) state. The Dunham coefficients and potential curve characterising this state were deduced from the observed spectra.

6

Highly-efficient fully-fiberized mid-infrared differential frequency generation source and its application to laser spectroscopy

100%

Krzempek K. , Dudzik G. , Hudzikowski A. , Gluszek A. , Abramski K.

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tom Vol. 25, No. 4

269--274

EN

Widely-tunable, fully-monolithic, mid-infrared (mid-IR) deference frequency generation source (DFG) is presented. By using a custom designed fiber-pigtailed periodically poled lithium niobate (PPLN) crystal module the idler beam was generated with an efficiency of 21%/W, yielding 2.6 mW of optical output power. The proposed all-fiber configuration radically simplified the optical frequency conversion setup, making it robust and easily configurable. The usefulness of the constructed source was verified by performing simultaneous wavelength modulation spectroscopy (WMS) laser trace gas detection of methane, near 2999 cm⁻¹, and ethane, near 2997 cm⁻¹, via two independently generated, tunable idler beams.

7

Frequency-multiplexed gas sensing using chirped laser molecular spectroscopy

100%

Tomaszewska D. , Jaworski P. , Nikodem M.

Opto-Electronics Review

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2018

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tom Vol. 26, No. 2

103--107

EN

A method for frequency-multiplexed multi-sample gas sensing is presented. It enables measuring multiple samples placed simultaneously in the setup, without any optical or mechanical switching. Samples are measured using heterodyne detection and signal from each sensing path is encoded at different carrier frequency. Subsequently, a signal from particular sample is retrieved through heterodyne beatnote demodulation at unique frequency. This technique is particularly suitable for real-time calibration of the sensor through a sequential (or simultaneous) detection of three signals: from unknown sample, reference sample and baseline. Basic setup is demonstrated and proof-of-concept experiments are presented. Very good agreement with spectra measured using standard tunable diode absorption spectroscopy is obtained.

8

Laser Photoacoustic Spectroscopy of the Piezoceramic Materials

100%

Mityurich G. S. , Aleksiejuk M. , Astakhov P. V. , Serdyukov A. N.

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tom Vol. 54, iss. 4

889-894

EN

The aim of the work is the investigation of photoacoustic transformation in piezoceramic materials and piezocrystals of various classes of symmetry. It is considered the case thermal mechanism of excitation of thermoelastic waves by various Bessel light beams polarization modes. Within the range of modulation frequency 100kHz- 1MHz the resonance phenomena are found. It’s showed that the amplitude of the resonance curves substantially depends on the radial distribution of the velocity of the Bessel light beams energy dissipation, on the type of polarization modes and on the geometric dimensions of the piezoelectric crystal, which acts also as a piezodetector. We can state that the results obtained by the resonance photoacoustic transformation can be used to improve the resolution of methods of photoacoustic spectroscopy and microscopy.

PL

Celem pracy są badania nad fotoakustyczną transformacją w materiałach piezoceramicznych oraz piezokryształach o różnych klasach symetrii. W pracy rozpatrywano termiczny mechanizm wzbudzania termosprężystych fal przez różne mody polaryzacyjne wiązek Bessela. W zakresie częstotliwości modulacji 100kHz-1MHz obserwowano zjawiska rezonansu. Wykazano, iż amplituda krzywych rezonansu w znacznym stopniu zależy od radialnego rozdziału prędkości rozpraszania energii wiązek Bessela, od typu modów polaryzacyjnych oraz od wymiarów geometrycznych kryształu piezoelektrycznego, który pełni także funkcje piezodetektora.

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Komputerowy system kontroli eksperymentu i akwizycji sygnałów spektroskopowych

75%

Buczek A. , Szawioła G. , Stachowska E. , Koczorowski W. , Walaszyk A. , Stefańska D. , Jarosz A. , Furmann B.

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2008

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tom Vol. 49, nr 6

193-195

PL

W artykule przedstawiono uniwersalny komputerowy system pomiarowy przeznaczony do spektroskopowych badań właściwości materii. Zastosowane w nim procedury pomiarowe i algorytmy mogą służyć do konstrukcji sensorów pomiarowych wykorzystujących fizyczne efekty kwantowe.

EN

We present an universal measurement system for spectroscopic investigations. Procedures and algorithms included may serve in the construction of sensors based on quantum effects.

10

Układy sterowania laserami kaskadowymi

75%

Bielecki Z. , Szabra D. , Nowakowski M. , Mikołajczyk J. , Wojtas J.

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2013

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tom R. 89, nr 10

43-46

PL

W pracy przedstawiono układy sterowania laserami kaskadowymi (quantum cascade lasers – QCL) pod kątem ich zastosowania w dwóch technikach; spektroskopii strat we wnęce optycznej oraz spektroskopii wieloprzejściowej. W trakcie projektowania tych sterowników, szczególną uwagę zwrócono zarówno na parametry czasowo-energetyczne wytwarzanych sygnałów, oraz na możliwości zastosowania dwóch technik przestrajania promieniowania laserowego tzn. wewnątrzimpulsowej lub międzyimpulsowej. Przeprowadzono również wstępne badania, które umożliwiły określenie właściwości tych układów oraz dały podstawę do opracowania kompaktowych sterowników laserów QCL.

EN

Quantum cascade laser drivers for absorption spectroscopy - the paper presents the fundamental aspects of optical spectroscopy using quantum cascade lasers. Two driving systems were described in terms of both QCL research and QCL applications in cavity ring down and multipass techniques. During drivers designing, the particular attention was given not only to energy-time parameters range (power, frequency, pulse duration, rise time). There were also adapted so-called spectral tuning techniques, i.e. intrapulse or interpulse wavelength modulation. Preliminary studies gave the possibility to determine the properties of designed drivers.

11

Ultrasensitive laser spectroscopy for breath analysis

51%

Wojtas J. , Bielecki Z. , Stacewicz T. , Mikołajczyk J. , Nowakowski M.

Opto-Electronics Review

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2012

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tom Vol. 20, No. 1

26-39

EN

At present there are many reasons for seeking new methods and technologies that aim to develop new and more perfect sensors for different chemical compounds. However, the main reasons are safety ensuring and health care. In the paper, recent advances in the human breath analysis by the use of different techniques are presented. We have selected non-invasive ones ensuring detection of pathogenic changes at a molecular level. The presence of certain molecules in the human breath is used as an indicator of a specific disease. Thus, the analysis of the human breath is very useful for health monitoring. We have shown some examples of diseases' biomarkers and various methods capable of detecting them. Described methods have been divided into non-optical and optical methods. The former ones are the following: gas chromatography, flame ionization detection, mass spectrometry, ion mobility spectrometry, proton transfer reaction mass spectrometry, selected ion flow tube mass spectrometry. In recent twenty years, the optical methods have become more popular, especially the laser techniques. They have a great potential for detection and monitoring of the components in the gas phase. These methods are characterized by high sensitivity and good selectivity. The spectroscopic sensors provide the opportunity to detect specific gases and to measure their concentration either in a sampling place or a remote one. Multipass spectroscopy, cavity ring-down spectroscopy, and photo-acoustic spectroscopy were characterised in the paper as well.