‘Cinematic’ Imaging Reflectometer for Time-Resolved Measurements (Under Design)

QIKR |  ST-2 | STS

Instrument Description

QIKR will be a general-purpose, horizontal-sample-surface reflectometer consisting of two independently operable end stations – one with the incident beam directed up and one directed down. It will collect specular and off-specular reflectivity data faster than any other such instrument. Using pulse skipping (7.5 Hz), it will often be possible to collect complete specular reflectivity curves using a single instrument setting to provide “cinematic” operation, in which the user “videos” the sample undergoing time-dependent modification.

Samples in time-dependent environments, such as temperature, electrochemical, or when undergoing chemical alteration will be observed in real time with frame rates as fast as 1.0 Hz in some cases. Cinematic data acquisition promises to make time-dependent measurements routine, with time resolution specified during post-experiment data analysis.

Cinematic operation will be deployed to observe such processes in real time as in situ polymer diffusion and reaction, battery electrode charge-discharge cycles, hysteretic phenomena, membrane protein insertion into lipid layers, and lipid flip-flop.

Applications

Soft matter

  • Polymer diffusion
  • Chemical transformation of reactive films
  • Hydrogels
  • Fouling
  • Structure properties of films under shear
  • Synthetic membranes
  • Responsive films
  • Polymer brushes under shear
  • Surface modification
  • Reactions at oil-water interfaces

Energy materials

  • Solid-electrolyte interphase
  • Organic photovoltaics
  • Ionic liquids
  • Corrosion
  • Mesoporous films
  • Conjugated polymer films
  • Metal-harvesting polymers

Biomaterials

  • Model membranes
  • Lipid flip-flop
  • Structure of transmembrane peptides
  • Biocompatible coatings
  • Surfactant and phospholipid monolayers
  • Drug delivery
  • Protein conformation to membranes
  • Influence of synthetic nanoparticles on membrane structure

Specifications

Dynamic Range of a Specular Reflectivity Measurements

Specular reflectivity R(Q) is parameterized in terms of wavevector transfer Q, which depends on the angle of incidence of the neutron beam on the sample θ and the wavelength of the neutron λ,


The STS will deliver pulsed neutrons in a band of wavelengths determined by the pulse frequency f and the distance from the neutron source to the detector L. The dynamic range of a measurement at a single θ may be written

Planck’s constant h divided by the neutron mass m equals 3956.0 m Å Hz and λ_"min" is the minimum wavelength in the available band. A large dynamic range allows measurement of R(Q) in a single setting and enables cinematic operation.

Beam spectrum

Thermal, Cold

Moderator

Cylindrical Coupled Hydrogen (20 K)

Wavelength bandwidth

2.5 Å < λ < 25 Å (at 7.5 Hz on lower station)

Source-detector distance

20 m (lower station)

24 m (upper station)

Detector

 

Pixelated 2D PSD (<2×2 mm2 resolution)

Dynamic range

10


QIKR will collect data 25× faster than existing instruments over a sufficient dynamic range to enable cinematic measurements for most samples. Depending on the sample structural parameters of interest, single data set frame rates will range from seconds to minutes.