TY - JOUR AB - We report the influence of multiple plasmon losses on the dynamical diffraction of high-energy electrons, in a scanning transmission electron microscopy (STEM) study. Using an experimental setup enabling energy-filtered momentum-resolved STEM, it is shown that the successive excitation of up to five plasmons within the imaged material results in a subsequent and significant redistribution of low-angle intensity in diffraction space. An empirical approach, based on the convolution with a Lorentzian kernel, is shown to reliably model this redistribution in dependence of the energy-loss. Our study demonstrates that both the significant impact of inelastic scattering in low-angle diffraction at elevated specimen thickness and a rather straightforward model can be applied to mimic multiple plasmon scattering, which otherwise is currently not within reach for multislice simulations due to computational complexity. AU - Robert, H.L.* AU - Diederichs, B. AU - Muller-Caspary, K.* C1 - 67058 C2 - 53432 TI - Contribution of multiple plasmon scattering in low-angle electron diffraction investigated by energy-filtered atomically resolved 4D-STEM. JO - Appl. Phys. Lett. VL - 121 IS - 21 PY - 2022 SN - 0003-6951 ER - TY - JOUR AB - In this study, we present proof of concept for an x-ray detector. The hybrid device consists of a synthetic single crystal diamond in mechanical contact with a piezoelectric lithium niobate surface acoustic wave (SAW) delay line. Upon x-ray irradiation, the diamond crystal experiences a change in conductivity, which, in turn, very sensitively influences the SAW transmission on the delay line. This change in SAW attenuation is directly used to monitor the x-ray beam intensity. The SAW attenuation shows a monotonic variation with dose rate D in the studied range between 100 and 1800 μGy/s. While the response time leaves room for further improvement, the SAW detection principle offers the unique possibility for wireless remote powering and sensing. AU - Topaltzikis, D. AU - Wielunski, M. AU - Hörner, A.L.* AU - Küß, M.* AU - Reiner, A.* AU - Grünwald, T.* AU - Schreck, M.* AU - Wixforth, A.* AU - Rühm, W. C1 - 61762 C2 - 50140 CY - 1305 Walt Whitman Rd, Ste 300, Melville, Ny 11747-4501 Usa TI - Detection of x rays by a surface acoustic delay line in contact with a diamond crystal. JO - Appl. Phys. Lett. VL - 118 IS - 13 PB - Amer Inst Physics PY - 2021 SN - 0003-6951 ER - TY - JOUR AB - Hybrid optoacoustic and pulse-echo ultrasound imaging is an attractive multi-modal combination owing to the highly complementary contrast of the two techniques. Efficient hybridization is often hampered by significant dissimilarities between their optimal data acquisition and image formation strategies. Herein, we introduce an approach for combined optoacoustic and ultrasound imaging based on a plano-concave detector array design with a non-uniform pitch distribution. The hybrid design optimized for both modalities allows for maintaining an extended field of view for efficient ultrasound navigation while simultaneously providing broad tomographic coverage for optimal optoacoustic imaging performance. Imaging sessions performed in tissue-mimicking phantoms and healthy volunteers demonstrate that the suggested approach renders an enhanced imaging performance as compared with the previously reported hybrid optoacoustic and ultrasound imaging approaches. Thus, it can greatly facilitate clinical translation of the optoacoustic imaging technology by means of its efficient combination with ultrasonography, a well-established clinical imaging modality. AU - Dean-Ben, X.L. AU - Mercep, E.* AU - Razansky, D. C1 - 51308 C2 - 42948 CY - Melville TI - Hybrid-array-based optoacoustic and ultrasound (OPUS) imaging of biological tissues. JO - Appl. Phys. Lett. VL - 110 IS - 20 PB - Amer Inst Physics PY - 2017 SN - 0003-6951 ER - TY - JOUR AB - Non-contact optoacoustic imaging employing raster-scanning of a spherically focused air-coupled ultrasound transducer is showcased herein. Optoacoustic excitation with laser fluence within the maximal permissible human exposure limits in the visible and near-infrared spectra is applied to objects with characteristic dimensions smaller than 1 mm and absorption properties representative of the whole blood at near-infrared wavelengths, and these signals are shown to be detectable without contact to the sample using an air-coupled transducer with reasonable signal averaging. Optoacoustic images of vessel-mimicking tubes embedded in an agar phantom captured with this non-contact sensing technique are also showcased. These initial results indicate that an air-coupled ultrasound detection approach can be suitable for non-contact biomedical imaging with optoacoustics. AU - Dean-Ben, X.L. AU - Pang, G.A. AU - de Espinosa, F.M.* AU - Razansky, D. C1 - 46634 C2 - 37659 CY - Melville TI - Non-contact optoacoustic imaging with focused air-coupled transducers. JO - Appl. Phys. Lett. VL - 107 IS - 5 PB - Amer Inst Physics PY - 2015 SN - 0003-6951 ER - TY - JOUR AB - Ultrasonography and optoacoustic imaging share powerful advantages related to the natural aptitude for real-time image rendering with high resolution, the hand-held operation, and lack of ionizing radiation. The two methods also possess very different yet highly complementary advantages of the mechanical and optical contrast in living tissues. Nonetheless, efficient integration of these modalities remains challenging owing to the fundamental differences in the underlying physical contrast, optimal signal acquisition, and image reconstruction approaches. We report on a method for hybrid acquisition and reconstruction of three-dimensional pulse-echo ultrasound and optoacoustic images in real time based on passive ultrasound generation with an optical absorber, thus avoiding the hardware complexity of active ultrasound generation. In this way, complete hybrid datasets are generated with a single laser interrogation pulse, resulting in simultaneous rendering of ultrasound and optoacoustic images at an unprecedented rate of 10 volumetric frames per second. Performance is subsequently showcased in phantom experiments and in-vivo measurements from a healthy human volunteer, confirming general clinical applicability of the method. AU - Fehm, T. AU - Dean-Ben, X.L. AU - Razansky, D. C1 - 42743 C2 - 35544 TI - Four dimensional hybrid ultrasound and optoacoustic imaging via passive element optical excitation in a hand-held probe. JO - Appl. Phys. Lett. VL - 105 IS - 17 PY - 2014 SN - 0003-6951 ER - TY - JOUR AB - A miniaturized ultrasound sensor is demonstrated in a silicon-on-insulator platform. The sensor is based on a π-phase-shifted Bragg grating formed by waveguide corrugation. Ultrasound detection is performed by monitoring shifts in the resonance frequency of the grating using pulse interferometry. The device is characterized by measuring its response to a wideband acoustic point source generated using the optoacoustic effect. Experimental results show that the sensor's response is dominated by the formation of surface acoustic waves. AU - Rosenthal, A. AU - Omar, M. AU - Estrada, H. AU - Kellnberger, S. AU - Razansky, D. AU - Ntziachristos, V. C1 - 30589 C2 - 33723 CY - Melville TI - Embedded ultrasound sensor in a silicon-on-insulator photonic platform. JO - Appl. Phys. Lett. VL - 104 IS - 2 PB - Amer Inst Physics PY - 2014 SN - 0003-6951 ER - TY - JOUR AB - We subjected conductive matter and tissue to intermittent continuous-wave radiofrequency fields and investigated whether acoustic responses could be recorded. By placing samples in the near-field of the excitation, we observed frequency-domain acoustic responses from tissues responding to CW radiofrequency excitation. Frequency analysis revealed the generation of 2nd harmonic mechanical waves. This discovery of non-linear responses can lead to alternative measurement concepts of CW radiofrequency deposition in matter and tissues. We offer the theoretical mainframe and discuss sensing applications involving the direct measurement of second harmonic responses representative of CW RF energy deposition in matter. AU - Kellnberger, S. AU - Omar, M. AU - Sergiadis, G.* AU - Ntziachristos, V. C1 - 28203 C2 - 33016 TI - Second harmonic acoustic responses induced in matter by quasi continuous radiofrequency fields. JO - Appl. Phys. Lett. VL - 103 IS - 15 PB - Amer. Inst. Physics PY - 2013 SN - 0003-6951 ER - TY - JOUR AB - Strong reflection and scattering effects, arising at the boundaries of acoustically mismatched areas in living organisms, such as bones, lungs, and other air cavities, may introduce severe image artifacts into optoacoustic reconstructions. Yet, in many cases, an a priori knowledge on the location of strongly mismatched areas is available, either based on general anatomical knowledge or using other imaging modalities. In this letter, we suggest a statistical optoacoustic image reconstruction method, which uses a priori knowledge on the location of acoustic distortions in order to improve image quality and quantification. Significant improvements are showcased experimentally on tissue mimicking phantoms of different complexities. AU - Dean-Ben, X.L. AU - Ntziachristos, V. AU - Razansky, D. C1 - 5960 C2 - 28584 TI - Statistical optoacoustic image reconstruction using a-priori knowledge on the location of acoustic distortions. JO - Appl. Phys. Lett. VL - 98 IS - 17 PB - American Institut of Physics PY - 2011 SN - 0003-6951 ER - TY - JOUR AB - Neuroscience investigations may significantly benefit from the availability of accurate imaging methods of brain parameters in small animals. In this letter, we investigate the imaging performance of the recently introduced interpolated model-matrix inversion (IMMI), in quantitative optoacoustic imaging of the mouse head. We compare the findings of the method against back-projection inversion methods that have more commonly been considered. We find that cross-sectional images of the mouse head accurately match anatomical structures seen on cryosliced head images serving as the gold standard. Moreover, superior imaging performance is found for IMMI compared to previously reported optoacoustic imaging of the mouse head. AU - Jetzfellner, T. AU - Rosenthal, A. AU - Englmeier, K.-H. AU - Dima, A. AU - Angel Araque Caballero, M. AU - Razansky, D. AU - Ntziachristos, V. C1 - 5437 C2 - 28495 TI - Interpolated model-matrix optoacoustic tomography of the mouse brain. JO - Appl. Phys. Lett. VL - 98 IS - 16 PB - American Institute of Physics PY - 2011 SN - 0003-6951 ER - TY - JOUR AB - We present the real-time x-ray irradiation response of charge and pH sensitive solution gate AlGaN/GaN high electron mobility transistors. The devices show stable and reproducible behavior under and following x-ray radiation, including a linear integrated response with dose into the mu Gy range. Titration measurements of devices in solution reveal that the linear pH response and sensitivity are not only retained under x-ray irradiation, but an irradiation response could also be measured. Since the devices are biocompatible, and can be simultaneously operated in aggressive fluids and under hard radiation, they are well-suited for both medical radiation dosimetry and biosensing applications. AU - Hofstetter, M. AU - Howgate, J.* AU - Sharp, I.D.* AU - Funk, M. AU - Stutzmann, M.* AU - Paretzke, H.G. AU - Thalhammer, S. C1 - 1781 C2 - 27700 TI - Real-time x-ray response of biocompatible solution gate AlGaN/GaN high electron mobility transistor devices. JO - Appl. Phys. Lett. VL - 96 IS - 9 PB - American Institute of Physics PY - 2010 SN - 0003-6951 ER - TY - JOUR AB - In this letter we experimentally demonstrate the sensitivity and overall performance of iterative correction for light attenuation in optoacoustic tomography as a function of number of iterations and accuracy of the tissue optical properties estimations. Experimental optoacoustic data were obtained by circularly illuminating a tissue-mimicking phantom with a high intensity pulsed near infrared laser and measuring the subsequent acoustic waves using a broadband acoustic hydrophone. We showcase an improvement in image fidelity and quantification due to the iterative inversion but find the method sensitive to the background optical properties and of a diverging behavior when increasing the number of iterations. AU - Jetzfellner, T.* AU - Razansky, D.* AU - Rosenthal, A.* AU - Schulz, R.B.* AU - Englmeier, K.-H. AU - Ntziachristos, V. C1 - 1665 C2 - 26469 TI - Performance of iterative optoacoustic tomography with experimental data. JO - Appl. Phys. Lett. VL - 95 IS - 1 PB - Amer Inst Physics PY - 2009 SN - 0003-6951 ER - TY - JOUR AB - Gas phase ionization mass spectrometry is shown to provide means for exploring the processes that control the retention of 10 keV He+ implanted in Si at 45°. Blistering, observed in situ, was preceded by a long period of bombardment (70% of the critical fluence for blistering) during which implanted He was released at a rather high rate (~33% of the incident He flux). Assisted by the stress due to the growing bubbles, bombardment induced detrapping allows a large fraction of the implanted He atoms to migrate to the nearby surface and escape into vacuum. AU - Wittmaack, K. C1 - 873 C2 - 26330 SP - 1836-1841 TI - In situ observation of gas reemission and blister rupture during helium implantation in silicon. JO - Appl. Phys. Lett. VL - 52 IS - 5 PB - Amer Inst Physics PY - 2009 SN - 0003-6951 ER - TY - JOUR AB - We investigate the conductivity of single-stranded and double-stranded herring deoxyribose nucleic acid(DNA) in buffer solution spotted and dried on Aunanocontacts. We find an exponential increase of the conductivity with increasing humidity that is identical for single- and double-stranded DNA within the measurement accuracy. While the small conductivity of dry DNA is comparable to that of a large band-gap semiconductor, we attribute the increase at high humidity levels to water molecules accumulated at the phosphate backbone. For high humidities we observe s-shaped current-voltage characteristics that can be well explained by the dissociation of water attached to the DNA molecules. AU - Kleine-Ostmann, T.* AU - Jördens, C.* AU - Baaske, K.* AU - Weimann, T.* AU - Hrabě de Angelis, M. AU - Koch, M.* C1 - 3052 C2 - 23640 TI - Conductivity of single-stranded and double-stranded deoxyribose nucleic acid under ambient conditions: The dominance of water. JO - Appl. Phys. Lett. VL - 88 IS - 10 PY - 2006 SN - 0003-6951 ER - TY - JOUR AB - Sputter removal of thin overlayers of Cu on Si was studied using 10 keV O+ 2 primary ions at near‐normal incidence. The decay length λ, which characterizes the exponential fall‐off of the Cu signal, was found to depend upon the carrier type, the dopant concentration, the polarity and strength of the electric field above the (n type) samples, and the intensity of light directed at the (p type) samples, the λ values varying between 0.4 and 2.2 μm. A similar dependence on sample and bombardment parameters was observed for the ion‐induced electron emission coefficient γ which ranged from 0.05 to 3 electrons/O+ 2 ion. The results suggest that the internal electrical field strength established in the ion‐bombarded sample is largely determined by the effective rate of electron emission. The field strength across the oxide controls the transport of positively charged Cu impurities through this region and thus also determines the Cu removal rate. AU - Wittmaack, K. AU - Homma, Y. C1 - 19098 C2 - 12153 SP - 2138-2140 TI - Correlation Between the O2+ Induced Electron Emission Coefficient and the Removal Rate of Cu Impurities Segregated at the SiO2/Si Interface. JO - Appl. Phys. Lett. VL - 58 IS - 19 PY - 1991 SN - 0003-6951 ER - TY - JOUR AB - Sputter removal of thin overlayers of Cu on Si was studied using 10 keV O+ 2 primary ions at near-normal incidence. The decay length λ, which characterizes the exponential fall-off of the Cu signal, was found to depend upon the carrier type, the dopant concentration, the polarity and strength of the electric field above the (n type) samples, and the intensity of light directed at the (p type) samples, the λ values varying between 0.4 and 2.2 μm. A similar dependence on sample and bombardment parameters was observed for the ion-induced electron emission coefficient γ which ranged from 0.05 to 3 electrons/O+ 2 ion. The results suggest that the internal electrical field strength established in the ion-bombarded sample is largely determined by the effective rate of electron emission. The field strength across the oxide controls the transport of positively charged Cu impurities through this region and thus also determines the Cu removal rate. AU - Wittmaack, K. AU - Homma, Y. C1 - 40774 C2 - 38045 SP - 2138-2140 TI - Correlation between the O+ 2 induced electron emission coefficient and the removal rate of Cu impurities segregated at the SiO 2/Si interface. JO - Appl. Phys. Lett. VL - 58 IS - 19 PY - 1991 SN - 0003-6951 ER - TY - JOUR AB - We have assembled a dual-beam system which allows solid samples to be analyzed by Rutherford backscattering spectrometry (RBS) at deliberately chosen stages of in situ sputter etching by low-energy ion bombardment. Using the novel setup we demonstrate that, for a large variety of samples, the analytical potential of conventional RBS can be extended remarkably. Apart from the obvious possibility of increasing the accessible depth of analysis, three specific advantages are illustrated: (i) removal of the interference between the signals due to buried dopants and a (low-mass) substrate, (ii) decoupling of the mass and the energy scale, and (iii) high-resolution depth analysis of deep-lying structures (glancing angle RBS) with the ability to circumvent the problems usually associated with sputter-related mixing effects. AU - Wittmaack, K. AU - Menzel, N. C1 - 41654 C2 - 36161 SP - 1708-1710 TI - Significantly extended analytical potential of Rutherford backscattering spectrometry by in situ combination with low-energy sputtering. JO - Appl. Phys. Lett. VL - 53 IS - 18 PY - 1988 SN - 0003-6951 ER - TY - JOUR AU - Wittmaack, K. AU - Menzel, N. C1 - 18322 C2 - 9228 SP - 815-817 TI - Exceptionally Pronounced Redistribution of Silver in Oxygen Bombarded Silicon. JO - Appl. Phys. Lett. VL - 50 PY - 1987 SN - 0003-6951 ER - TY - JOUR AB - Limitations in dynamic range previously experienced in SIMS depth profiling are shown to be caused by neutral projectiles present in the primary ion beam. Dynamic ranges of about 106 can be achieved if (i) the final section of the primary beam line and the sample are immersed in a UHV ambient (<10-6 Pa) and (ii) the beam traversing this region is deflected or offset from the gun axis so that energetic neutrals produced in the beam line do not hit the sample. AU - Wittmaack, K. AU - Clegg, J.B.* C1 - 41126 C2 - 38153 SP - 285-287 TI - Dynamic range of 106 in depth profiling using secondary-ion mass spectrometry. JO - Appl. Phys. Lett. VL - 37 IS - 3 PY - 1980 SN - 0003-6951 ER - TY - JOUR AB - Entrapment of 10-160-keV xenon implanted under UHV conditions in polycrystalline aluminum has been investigated by Rutherford backscattering. The saturation xenon distributions were found to be strongly affected by radiation-enhanced outdiffusion. Different from silicon the loss of xenon from near-surface regions of aluminum increases with increasing ion energy. The results are explained in terms of spike-activated diffusion. AU - Wittmaack, K. AU - Blank, P. C1 - 42316 C2 - 38191 SP - 21-23 TI - Radiation-enhanced outdiffusion of xenon implanted in aluminum. JO - Appl. Phys. Lett. VL - 31 IS - 1 PY - 1977 SN - 0003-6951 ER -