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  • 1
    Electronic Resource
    Electronic Resource
    Sublinear absorption in OCS gas (1988)
    Springer
    Il nuovo cimento della Società Italiana di Fisica 10 (1988), S. 161-172 
    Details
    ISSN: 0392-6737
    Keywords: Multiphoton processes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Description / Table of Contents: Riassunto L'assorbimento sublineare dell'OCS allo stato gassoso è stato studiato utilizzando tecniche optoacustiche e misure di trasmissione. La migliore interpretazione dei dati sperimentali è ottenuta utilizzando un modello che considera il processo come la somma di assorbimenti ad uno e due fotoni.
    Abstract: Резюме С помощью оптоакустической техники и измерений прохождения экспериментально исследуется сублинейное поглощение в OCS газе. Наилучшая интерпретация экспериментальных результатов получается с помощью феноменологической модели, в которой процесс рассматривается как сумма поглощения одного и двух фотонов.
    Notes: Summary Sublinear absorption in OCS gas has been experimentally studied in detail by means of an optoacustic technique and transmission measurements. The best fit of the results is obtained by a phenomenological model, that considers the process as the sum of one- and two-photon absorptions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02450097
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  • 2
    Electronic Resource
    Electronic Resource
    Resonant rayleigh scattering in semiconductor structures (1995)
    Springer
    Il nuovo cimento della Società Italiana di Fisica 17 (1995), S. 1487-1492 
    Details
    ISSN: 0392-6737
    Keywords: III-V semiconductors ; Electron states in low-dimensional structures (including, quantum wells, superlattices, layer structures, and intercalation compounds) ; Excitons and related phenomena (including electron-hole drops) ; Brillouin and Rayleigh scattering ; Conference proceedings
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Summary A detailed study of the relative role played by localized and/or propagating intermediate excitonic states in, resonant Rayleigh scattering (RRS) is presented for a large set of GaAs quantum well (QW) and bulk structures. We show that the two kinds of states contribute to RRS through different mechanisms. We concluded that RRS occurs via localized states in QW heterostructures, very likely due to localization by the interface roughness, while bulk, crystals turn out to be better candidates for RRS via propagating states.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02457231
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  • 3
    Electronic Resource
    Electronic Resource
    Coherent hyper-raman scattering: An application to amorphous materials (1989)
    Springer
    Il nuovo cimento della Società Italiana di Fisica 11 (1989), S. 1451-1465 
    Details
    ISSN: 0392-6737
    Keywords: Infrared and Raman spectra and scattering ; Nonlinear optics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Description / Table of Contents: Riassunto La diffusione Hyper-Raman coerente da polaritoni eccitati mediante assorbimento di un impulso laser infrarosso offre notevoli vantaggi rispetto alla diffusione Hyper-Raman termica. Essa consente uno studio preciso dei modi polari negli amorfi e nei liquidi dove risultano proibiti nelle transizioni Raman. Viene formulata una teoria classica per questo tipo di diffusione coerente ed i risultati vengono applicati allo studio sperimentale del polaritone a 1065 cm−1 nel quarzo amorfo. I dati sperimentali, con una precisione di due ordini di grandezza migliore che nei precedenti studi, mostrano che il polaritone si propaga nel vetro con un ben definito vettore d’onda. La curva di dispersione del polaritone e la sua larghezza nello spazio dei vettori d’onda può essere descritta mediante un modello a più oscillatori, tenendo conto dell’allargamento inomogeneo dei livelli derivante dal disordine.
    Abstract: Резюме Когерентное гипер-рамановское рассеяние на горячих поляритонах дает явные преимущества по сравнению с тепловым гиперрамановских рассеянием. Этот подход поэволяет исследовать полярные моды в жидкостях и аморфных материалах, где они эапрешены при рамановском рассеянии. Мы раэвиваем классическую теорию для этого нелинейного процесса и полученные реэультаты применяются к иоследованию псляритона при 1065 cm−1 в амопфном кварце. Эксперименталвные данные, имеюшие точносты на два порядка лучше предыдуших реэультатов, покаэывают, что поляритоны распространяются в стекле с хорошо определенным волновым вектором. Дисперсионная кривая поляритона и ее шириина в пространстве волновых векторов может быты олисана с помощью многоосцилляторной модели, которая учитывает неоднородную ширину уровней, воэникющую иэ-эа неупорядоченности.
    Notes: Summary Coherent Hyper-Raman scattering from hot polaritons gives conspicuous advantages with respect to thermal Hyper-Raman scattering. It allows a precise study of polar modes in liquids and amorphous materials, where they are forbidden in Raman scattering. We give a classical theory for this nonlinear process and the results are applied to the study of the polariton at 1065 cm−1 in amorphous quartz. The experimental data, having a precision two orders of magnitude better than in previous studies, show that the polaritons propagate in the glass with a well-defined wave vector. The dispersion curve of the polariton and its width in the wave vector space can be described by means of a multioscillator model taking into account the inhomogenous width of the levels originated from disorder.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02450505
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  • 4
    Electronic Resource
    Electronic Resource
    Anomalies in the polarized raman spectrum of crystal quartz (1990)
    Springer
    Il nuovo cimento della Società Italiana di Fisica 12 (1990), S. 915-925 
    Details
    ISSN: 0392-6737
    Keywords: Infrared and Raman spectra and scattering ; Nonlinear optics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Summary By means of coherent Raman scattering we have measured in quartz the dispersion of the elements of the Raman tensor in the range (900÷1070) cm−1. The results determine with good accuracy the relative contribution of the various modes to the second-order nonlinear susceptibility. For some elements of the Raman tensor the present results greatly improve the precision of data already known; for others the dispersion and the relative strengths have been measured for the first time. In particular, a strong, frequency-dependent, asymmetry of the Raman tensor has been evidentiated; this asymmetry is interpreted in terms of optical Raman activity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02453038
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  • 5
    Electronic Resource
    Electronic Resource
    Carrier recombination dynamics in self-ordered InAs quantum dots (1995)
    Springer
    Il nuovo cimento della Società Italiana di Fisica 17 (1995), S. 1371-1375 
    Details
    ISSN: 0392-6737
    Keywords: III–V semiconductors ; III–V compounds and systems ; Electron states in low-dimensional structures (including quantum wells, superlattices, layer structures, and intercalation compounds) ; Conference proceedings
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Summary A photoluminescence study of self-ordered InAs quantum dots grown by molecular beam epitaxy on a GaAs substrate is reported. Short pulses and high excitations have been used in order to observe emission from higher states of the quantum dots. The energy spacing between adjacent transitions seems to be of the order of 40–50 meV for dot diameters around 20 nm. The photoluminescence decay time from the ground state is of the order of 650–700 ps and decreases down to roughly 100 ps for the highest confined states. A cascade-like mechanism for the carrier relaxation in these structures is strongly suggested by the time-resolved data.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02457212
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  • 6
    Electronic Resource
    Electronic Resource
    Raman scattering by hot polaritons in NaClO3 (1985)
    Springer
    Il nuovo cimento della Società Italiana di Fisica 5 (1985), S. 77-88 
    Details
    ISSN: 0392-6737
    Keywords: Infra-red and Raman spectra and scattering
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Description / Table of Contents: Riassunto Usando tecniche di mescolamento non lineare di radiazione visibile e IR, cioè diffusione Raman coerente da polaritoni pompati da un laser a CO2, è stato possibile ottenere spettri ad alta risoluzione dei modiF di un cristallo di NaClO3 nella regione (907÷957) cm−1, dove sono presenti piú modi isotopici. La misura così ottenuta, in modo indipendente, dell'indice di rifrazione e dell'assorbanza del cristallo permette una determinazione accurata della curva di dispersione e della sua larghezza nello spazio dei momentiq. I dati sperimentali confermano l'esistenza ci un modo isotopico localizzato a 931 cm−1 e di un modo fortemente smorzato intorno a 960 cm−1. Infine, è stata ottenuta per la prima volta una misura accurata della dispersione della polarizzabilità non lineare del second'ordine nella stessa regione di energie.
    Abstract: Резюме Используя технику нелинейного смешивания инфракрасного и видимого излучений, т.е. когерентное рамановское рассеяние на поляритонах, образованных CO2 лазером, оказывается возможным получение спектров с высоким разрешением дляF-мод кристалла NaClO3 в области (907÷957) см−1, где имеется несколько изотропных мод. Проведенное независимое измерение показателя преломления и поглощения позволяет нам аккуратно определить дисперсионную кривую и ее ширину вq-пространстве. Экспериментальные данные подтверждают существование локализованной моды при 931 см−1 и сильно затухающей моды вблнзи 960 см−1. В заключение, впервые проведено точное измерение дисперсии нелинейной поляризуемости второго порядка в той же области энергий.
    Notes: Summary By nonlinear mixing of IR and visible radiation,i.e. coherent Raman scattering by polaritons driven by a CO2 laser, it has been possible to get high-resolution spectra for theF-modes of a NaClO3 crystal in the region (907÷957) cm−1, where several isotopic modes are present. The obtained independent measurement of the refractive index and absorbance allows an accurate determination of the polariton dispersion curve and its width inq-space. The experimental data confirm the existence of a localized isotopic mode at 931 cm−1 and a strongly damped isotopic mode near 960 cm−1. Finally, an accurate measurement of the dispersion of the second-order nonlinear polarizability in the same energy region has been obtained for the first time.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02453205
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  • 7
    Electronic Resource
    Electronic Resource
    Raman scattering by hot and thermal polaritons in crystal quartz (1984)
    Springer
    Il nuovo cimento della Società Italiana di Fisica 4 (1984), S. 453-468 
    Details
    ISSN: 0392-6737
    Keywords: Infra-red and Raman spectra and scattering
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Description / Table of Contents: Riassunto Mescolamento non lineare di radiazioni IR e visibile, cioè diffusione Raman coerente da polaritoni generati da un laser a CO2, è stato utilizzato per ottenere la curva di dispersione e la sua larghezza nello spazio dei momentiq del polaritone associato al fonone a 1065 cm−1, di simmetriaE, in un cristallo di quarzo. Si mostra nell'articolo che è possibile ottenere, in questo modo, un metodo diretto per determinare, con grande precisione, l'indice di rifrazione e l'assorbanza di un cristallo. I risultati sono confrontati con dati sperimentali assai accurati ottenuti mediante diffusione Raman dei polaritoni in equilibrio termico; si trova un ottimo accordo tra i risultati delle due misure. Si mostra infine che tali tecniche di mescolamento non lineare sono del tutto compatibili con un semplice modello di diffusione di luce da polaritoni pompati.
    Abstract: Резюме Исполйзуется нелинейное смешивание инфракрасного и видимого излучений, т.е. когерентное романовскоие рассеяние на поляритонах, образованных CO2 лазером, для получения дисперсионной кривой и ее ширины вq-пространстве поляритонов, связанных сE-фононом при 1065 см−1, в кристаллическом кварце. В статйе показывается, что в таком полходе может быть получен прямой метод для независимого определения показателя преломления и поглощения кристалла с высокой точностью. Полученные результаты сравниваются с данными для рамановского рассеяния на поляритонах в тепловом равновесии. Получается очень хорошее согласие между двумя измерениями. Показывается, что техника нелинейного смешивания согласуется с простой картиной рассеяния света на горячих поляритонах.
    Notes: Summary Nonlinear mixing of IR and visible radiation,i.e. coherent Raman scattering by polaritons driven by a CO2 laser, has been used to obtain the dispersion curve and its width inq-space of the polariton associated to theE-phonon at 1065 cm−1 in crystal quartz. It is shown in this paper that a direct method to determine indipendently, with high precision, the refractive index and absorbance of a crystal can be obtained in this way. The results are compared with accurate data obtained from Raman scattering by polaritions in thermal equilibrium and very good agreement is found between the two measurements. It is finally shown that nonlinear-mixing techniques turn out to be completely consistent with the simple picture of scattering of light by hot polaritons.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02450603
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  • 8
    Electronic Resource
    Electronic Resource
    Thermally activated carrier transfer and luminescence line shape in self-organized InAs quantum dots (1996)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 69 (1996), S. 3354-3356 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We investigated the temperature dependence (10–180 K) of the photoluminescence (PL) emission spectrum of self-organized InAs/GaAs quantum dots grown under different conditions. The temperature dependence of the PL intensity is determined by two thermally activated processes: (i) quenching due to the escape of carriers from the quantum dots and (ii) carrier transfer between dots via wetting layer states. The existence of different dot families is confirmed by the deconvolution of the spectra in gaussian components with full width half maxima of 20–30 meV. The transfer of excitation is responsible for the sigmoidal temperature dependence of the peak energies of undeconvoluted PL bands. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.117304
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  • 9
    Electronic Resource
    Electronic Resource
    Growth patterns of self-assembled InAs quantum dots near the two-dimensional to three-dimensional transition (1997)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 70 (1997), S. 3140-3142 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Self-assembled InAs quantum dots have been grown by molecular beam epitaxy in such a way as to obtain a continuous variation of InAs coverages across the wafer. Structured photoluminescence spectra are observed after excitation of a large number of dots; deconvolution into Gaussian components yields narrow emission bands (full width at half-maximum 20–30 meV) separated in energy by an average spacing of 30–40 meV. We ascribe the individual bands of the photoluminescence spectra after low excitation to families of dots with similar shapes and with heights differing by one monolayer, as strongly supported by numerical calculations of the fundamental electronic transitions in quantum dot structures. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.119114
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  • 10
    Electronic Resource
    Electronic Resource
    Two-exciton spectra of HCl and HBr crystals
    Amsterdam : Elsevier
    Chemical Physics 88 (1984), S. 375-389 
    Details
    ISSN: 0301-0104
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    URL: http://linkinghub.elsevier.com/retrieve/pii/0301-0104(84)87004-4
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