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Broadband seismometers measure ground motion across a broad range of frequencies, detecting not only earthquakes, but also storms, footsteps, loud noises, and even passing vehicles!  These instruments measure ground motion (as movement velocity) as small as micrometers per second, and in three dimensions.  Motion is recorded electronically as a suspended weight moves independently from the casing, passing a magnet through coiled wires, inducing an electrical current.  To collect meaningful information on ground motion, these broadband seismometers are buried in locations of geologic interest for periods of time ranging from months to several years.

The Geode seismic acquisition system includes 24 sensitive geophones that measure ground motion at very high frequencies at evenly-spaced distances.  Signals recorded by this system are typically from a man-made source, such as a weight-drop or the impact of a sledgehammer on a metal plate.  Timing of this signal is precisely synchronized with all 24 geophones to create records of how energy is transmitted through the ground, and how it reflects off of subsurface interfaces.

The G-857 is a proton procession magnetometer, which measures magnetic fields to a sensitivity of tenths of a nanoTesla.  The sensor is filled with a fluid containing hydrogen atoms.  A strong magnetic field is created around the fluid, causing the protons of the hydrogen atoms to align within the field.  When the artificial magnetic field is released, the protons realign with the natural ambient magnetic field, creating an electrical current that is recorded by the instrument and converted to magnetic field strength.  By making measurements like this in many locations, we can create a map showing how the magnetic field varies spatially.  This can reveal changes in subsurface geology, buried objects containing small amounts of ferrous material, or even disturbed soils.

Inductively coupled plasma mass spectrometers (ICP-MS) measure the concentrations of trace and major elements in liquid or solid samples. The Varian 820-MS ICP-MS is set up to process data from solutions using the Cetac ASX-520 autosampler or solids using the New Wave UP 213nm laser ablation system. This laser ablation system allows researchers to get pinpoint, in situ data from solid samples like rocks, glass, and crystals. Both the Varian and Argilent instruments housed in this lab are quadrupole ICP-MS systems, so researchers can measure the majority of the periodic table in just seconds.

Instrument statistics

Download the Bruker 820-MS brochure.

How it works

A beam of high-energy electrons is produced by a field emission gun at the top of the column.  This focused beam continuously rasters back and forth across the sample. Interactions between the electron beam and the sample result in different types of emissions that are measured by a series of detectors located within the sample chamber. 

The SEM is equipped with two basic detectors that produce images from secondary electrons and backscattered electrons. Secondary electron imaging provides good three-dimensional topographic views of the sample. Backscattered electron images show less-defined topography but clearly display differences in elemental compositions because higher-atomic-number elements appear brighter. 
 

Three auxiliary detectors greatly enhance the analytical capabilities of this system. Imaging using the Centaurus cathode luminescence (CL) detector reveals chemical variations within individual grains containing elements that release some of the energy imparted by the electron beam back as visible light. For chemical analyses, characteristic X-ray energies emitted by each element within the sample are collected by the Oxford EDS detector and translated into elemental percentages and plots by Aztec software. This software also interfaces with the Oxford EBSD detector to determine phase and lattice orientations of crystalline substances by collecting back-scattered electrons diffracted in phase off a tilted sample.  

Instrument statistics

Quantitative analyses are performed at 20 kV using a 10 mm working distance, and are collected for 200 seconds of live time.
 

How it works

Oxygen, carbon, or nitrogen must be separated from samples by some chemical method (such as combustion, dissolution in acids, or fusing with a laser in the presence of an oxidizer). Gases are then purified in a vacuum line (glass trellis-work in picture) or within the elemental analyzer. The purified gases are then introduced into the mass spectrometer, either by using the dual-inlet system or continuous flow mode, where they are bombarded by electrons and ionized. The ions travel down a flight tube and are separated according to mass by an electromagnet. The ions are then detected in Faraday cups at the end of the flight tube. The isotope ratio is calculated from the charge of the ions at the end of the flight tube. See Finnigan's brochure for instrument and analytical statistics.

´ó·¢²ÊƱ’s system uses Cu Kα radiation that has a wavelength of 1.54Ã…. Analyses are commonly run using a 40kV 45mA x-ray tube voltage, a 0.04° soller slit, 1° divergence and antiscatter slits, and a 1/2° (for powder) or 1/4° (for clays) receiving slit.

How it works

During x-ray diffraction analysis, x-ray beams are reflected off the parallel atomic layers within a mineral over a range of diffraction angles. Because the x-ray beam has a specific wavelength, for any given 'd-spacing' (distance between adjacent atomic planes) there are only specific angles at which the exiting rays will be 'in phase' and therefore rays will be picked up by the detector producing a peak on the 'diffractogram.' Like a human fingerprint, every mineral has its own distinct set of diffraction peaks that can be used to identify it.

Related research

This system has been used extensively to collect data for a wide variety of research. Some of the major projects include:

NSF/CRUI — Study on acid deposition and calcium depletion in Adirondack soils
ILWAS — Integrated Lake Watershed Acidification Study — study of the effects of acid deposition on three Adirondack lakes
RILWAS — Regional Integrated Lake Watershed Acidification Study: a study of the effects of acid deposition on lakes in the Adirondacks and various other locations across the United States, Canada, and Europe
ALBIOS — Aluminum Biogeochemistry Study: a study of the effects of aluminum on forested ecosystems
IFS — Integrated Forest Study, an international effort to study the effects of acid deposition on forest ecosystems throughout the United States, Canada, and Europe
DOE — study of the distribution of Cesium-137 in lake-bottom sediments

Using the same principle of ´ó·¢²ÊƱ’s laboratory x-ray fluorescence spectrometer, this hand-held unit uses high-energy x-ray photons to analyze geologic samples. The energy of secondary x-rays emitted by the sample during analysis is specific to each particular element, which can be used to determine its chemical composition.

This lab has been used extensively to collect data for a wide variety of research projects including:

NSF/CRUI — Study on Acid Deposition and Calcium Depletion in Adirondack Soils
DOE study of the distribution of Cesium-137 in lake bottom sediments
IFS — Integrated Forest Study: an international effort to study the effects of acid deposition on forest ecosystems throughout the United States, Canada, and Europe
ALBIOS — Aluminum Biogeochemistry Study - a study of the effects of aluminum on forested ecosystems
RILWAS — Regional Integrated Lake Watershed Acidification Study - a study of the effects of acid deposition on lakes in the Adirondacks and various other locations across the United States, Canada, and Europe
ILWAS — Integrated Lake Watershed Acidification Study - a study of the effects of acid deposition on three Adirondack lakes

• Seismicity of Upstate New York