scholarly journals Exploring the hidden depth by confocal Raman experiments with variable objective aperture and magnification

2021 ◽  
Author(s):  
Barbara Boldrini ◽  
Edwin Ostertag ◽  
Karsten Rebner ◽  
Dieter Oelkrug
Keyword(s):  
Depth Resolution ◽  
Sample Surface ◽  
Object Size ◽  
High Magnification ◽  
Excitation Beam ◽  
Depth Profiles ◽  
Fill Fraction ◽  
Deep Sample ◽  
Focusing Lens ◽  
Signal Intensities

AbstractThe article analyzes experimentally and theoretically the influence of microscope parameters on the pinhole-assisted Raman depth profiles in uniform and composite refractive media. The main objective is the reliable mapping of deep sample regions. The easiest to interpret results are found with low magnification, low aperture, and small pinholes. Here, the intensities and shapes of the Raman signals are independent of the location of the emitter relative to the sample surface. Theoretically, the results can be well described with a simple analytical equation containing the axial depth resolution of the microscope and the position of the emitter. The lower determinable object size is limited to 2–4 μm. If sub-micrometer resolution is desired, high magnification, mostly combined with high aperture, becomes necessary. The signal intensities and shapes depend now in refractive media on the position relative to the sample surface. This aspect is investigated on a number of uniform and stacked polymer layers, 2–160 μm thick, with the best available transparency. The experimental depth profiles are numerically fitted with excellent accuracy by inserting a Gaussian excitation beam of variable waist and fill fraction through the focusing lens area, and by treating the Raman emission with geometric optics as spontaneous isotropic process through the lens and the variable pinhole, respectively. The intersectional area of these two solid angles yields the leading factor in understanding confocal (pinhole-assisted) Raman depth profiles. Graphical abstract

The Basic Physical Principles of Ion, Electron, and X-Ray Detectors and Their Application to Microanalysis

1985 ◽  
Vol 43 ◽  
pp. 154-157
Author(s):  
A.J. Tousimis
Keyword(s):  
Ion Beam ◽  
Depth Resolution ◽  
Sample Surface ◽  
High Energy ◽  
X Rays ◽  
X Ray ◽  
Electrons And Ions ◽  
Spatial Depth ◽  
Minimum Surface Area ◽  
Physical Principles

An integral and of prime importance of any microtopography and microanalysis instrument system is its electron, x-ray and ion detector(s). The resolution and sensitivity of the electron microscope (TEM, SEM, STEM) and microanalyzers (SIMS and electron probe x-ray microanalyzers) are closely related to those of the sensing and recording devices incorporated with them.Table I lists characteristic sensitivities, minimum surface area and depth analyzed by various methods. Smaller ion, electron and x-ray beam diameters than those listed, are possible with currently available electromagnetic or electrostatic columns. Therefore, improvements in sensitivity and spatial/depth resolution of microanalysis will follow that of the detectors. In most of these methods, the sample surface is subjected to a stationary, line or raster scanning photon, electron or ion beam. The resultant radiation: photons (low energy) or high energy (x-rays), electrons and ions are detected and analyzed.

Depth Profiling Investigation of Seawater Using Combined Multi-Optical Spectrometry

2020 ◽  
Vol 74 (5) ◽  
pp. 563-570 ◽  
Author(s):  
Wangquan Ye ◽  
Jinjia Guo ◽  
Nan Li ◽  
Fujun Qi ◽  
Kai Cheng ◽  
...  
Keyword(s):  
Deep Sea ◽  
Depth Profiling ◽  
Deep Ocean ◽  
Euphotic Zone ◽  
Depth Resolution ◽  
Remotely Operated Vehicle ◽  
Sea Trial ◽  
Depth Profiles ◽  
Diving Depth ◽  
Optical Spectrometry

Depth profiling investigation plays an important role in studying the dynamic processes of the ocean. In this paper, a newly developed hyphenated underwater system based on multi-optical spectrometry is introduced and used to measure seawater spectra at different depths with the aid of a remotely operated vehicle (ROV). The hyphenated system consists of two independent compact deep-sea spectral instruments, a deep ocean compact autonomous Raman spectrometer and a compact underwater laser-induced breakdown spectroscopy system for sea applications (LIBSea). The former was used to take both Raman scattering and fluorescence of seawater, and the LIBS signal could be recorded with the LIBSea. The first sea trial of the developed system was taken place in the Bismarck Sea, Papua New Guinea, in June 2015. Over 4000 multi-optical spectra had been captured up to the diving depth about 1800 m at maximum. The depth profiles of some ocean parameters were extracted from the captured joint Raman–fluorescence and LIBS spectra with a depth resolution of 1 m. The concentrations of [Formula: see text] and the water temperatures were measured using Raman spectra. The fluorescence intensities from both colored dissolved organic matter (CDOM) and chlorophyll were found to be varied in the euphotic zone. With LIBS spectra, the depth profiles of metallic elements were also obtained. The normalized intensity of atomic line Ca(I) extracted from LIBS spectra raised around the depth of 1600 m, similar to the depth profile of CDOM. This phenomenon might be caused by the nonbuoyant hydrothermal plumes. It is worth mentioning that this is the first time Raman and LIBS spectroscopy have been applied simultaneously to the deep-sea in situ investigations.

High Resolution Auger Depth Profiles Using a Dual Ion Gun System

1985 ◽  
Vol 54 ◽  
Author(s):  
S. Ingrey ◽  
J.P.D. Cook
Keyword(s):  
Electron Beam ◽  
Depth Profiling ◽  
Depth Resolution ◽  
Grazing Incidence ◽  
Low Energy ◽  
Multilayer Structures ◽  
Dramatic Decrease ◽  
Depth Profiles ◽  
Order Of Magnitude ◽  
Magnitude Improvement

A dual ion gun system has been proposed (D.E. Sykes et al, Appl. Surf. Sci. 5(1980)103) to reduce texturing and improve depth resolution during Auger sputter depth profiling. We have evaluated this ion gun configuration by profiling a variety of multilayer structures. With careful alignment of the guns, we have obtained a dramatic decrease in ion-induced texturing often seen when a single ion gun is used. This effect was particularly pronounced for polycrystalline Al films on Si where an order of magnitude improvement in depth resolution was achieved. Further refinements of the technique include the use of low energy (IkeV) grazing incidence xenon ions and a small electron beam probe area. Depth profiles obtained from Ni/Cr, W/Si, and GaAs/GaAlAs multilayer structures will also be discussed.

Capabilities and Merits of Long-term Bio-optical Moorings

Ocean Optics ◽  
1994 ◽  
Author(s):  
John Marra
Keyword(s):  
Time Resolution ◽  
Spatial Data ◽  
Depth Resolution ◽  
Point Of View ◽  
Phytoplankton Production ◽  
Mode Water ◽  
Depth Profiles ◽  
Geographic Coverage

There are primarily three ways in which the ocean can be sampled. First, depth profiles of water properties can be collected. The sampling resolution for depth profiles can be very high (<1 m), and time resolution can be good under some circumstances. But since relatively few stations can be completed, geographic coverage is generally poor. Variability in space can be optimized if data can be collected while the ship is underway. In this second sampling mode, water is pumped aboard for sampling, or else sensing instruments are towed behind the ship. This method vastly improves sampling horizontal variability; however, depth resolution is compromised, and measurements cannot be ordered in time. The third method is to place instruments in the ocean, either tethered to moorings or on drifters. While depth resolution is only moderately good (typically, tens of meters), and spatial data nonexistent, this method has the advantage, unobtainable with the other modes, of high resolution in time. While moorings and drifters have been in the repertoire of physical oceanographic sampling for some time, it is only recently that they have been used to sample biological and optical properties of the sea. In this chapter, I discuss the capabilities of this kind of sampling from the point of view of a recent program, the BIOWATT Mooring Experiment in 1987. One of the express purposes of this experiment was to expand the range of variables that can be measured from moored instrumentation. Here, I will show how the time resolution made possible with moored sensors allows the measurement of parameters of phytoplankton production on diurnal time scales, as well as allowing a look at seasonal variability. The BIOWATT Mooring Experiment was a collaboration among a large number of people, all of whom contributed to its success. It was the first deployment of a mooring with a variety of sensors and whose goal was to record the optical, biological, and physical variability over a seasonal cycle. The idea for this type of experiment for BIOWATT originated with Tom Dickey and his (then) graduate student, Dave Siegel.

Neutron Depth Profiling by Large Angle Coincidence Spectroscopy

1994 ◽  
Vol 354 ◽  
Author(s):  
J. Vacík ◽  
J. Cervenä ◽  
V. Hnatowicz ◽  
V. Havränek ◽  
D. Fink
Keyword(s):  
Analytical Method ◽  
Large Angle ◽  
Depth Profiling ◽  
Depth Resolution ◽  
Solid Material ◽  
Detection Sensitivity ◽  
Neutron Depth Profiling ◽  
Depth Profiles ◽  
Low Concentrations ◽  
Coincidence Spectroscopy

AbstractExtremely low concentrations of several technologically important elements (mainly lithium and boron) have been studied by a modified neutron depth profiling technique. Large angle coincidence spectroscopy using neutrons to probe solids with a thickness not exceeding several micrometers has proved to be a powerful analytical method with an excelent detection sensitivity. Depth profiles in the ppb atomic range are accessible for any solid material. A depth resolution of about 20 nanometers can be achieved.

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