Supported File Formats

MMI CSV

DENSsolutions MMI (Multi-Module Interface) heating controller export files.

Property Detail
Extension .csv
Requirements None - all information is contained within the CSV itself
Signals produced Multiple scalar (0Dts) signals - one per data column

Two-row header structure

MMI CSV files use a distinctive two-row header:

Row Content Example
1 Module group names Time, Dual Heater, Dual Heater, Sample Heater
2 Signal names (blank), Temperature Ambient, Resistance Ambient, …

Nexus combines both rows into signal names such as Dual Heater Temperature Ambient.

Auto-detection

Nexus distinguishes MMI files from Impulse CSV files automatically:

  • The first column header is Time (Impulse uses Timestamp).
  • At least one column group is Dual Heater or Sample Heater.

Timestamp handling

Timestamps are in ISO format (YYYY-MM-DD HH:MM:SS.ffffff). Nexus calculates elapsed seconds relative to the first row, correctly spanning midnight boundaries for multi-day experiments.

Unit detection

Units are inferred from signal names: Temperature → °C, Resistance → Ω, Voltage → V, Current → A, Pressure → bar.

Column filtering

Columns belonging to the No Module group are automatically excluded from the imported dataset.

Impulse CSV

DENSsolutions Impulse heating and biasing controller export files.

Property Detail
Extension .csv
Requirements Matching *_Metadata.log file in the same directory
Signals produced Multiple scalar (0Dts) signals - one per data column

Impulse CSV files require a metadata log file in the same folder. The metadata file must contain Experiment date: and Experiment time: fields. Without this file, loading will fail with a descriptive error message.

Validation requirements

Before parsing, Nexus validates the CSV file against these rules:

  1. Exactly one *_Metadata.log file must exist in the same directory.
  2. The metadata file must contain Experiment date: and Experiment time: fields.
  3. The CSV delimiter must be a comma (,).
  4. The CSV header must include Timestamp and Experiment time columns.

If any check fails, a toast notification describes the specific problem.

Timestamp calculation

Absolute timestamps are calculated by combining the experiment date/time from the metadata file with the per-row timestamp offsets in the CSV. The parser locates the experiment start row (where Experiment time = "00:00:00.000") and calculates offsets from there.

PSSession

PalmSens electrochemistry session files.

Property Detail
Extension .pssession
Format JSON-based
Signals produced Depends on experiment type

PSSession files are JSON-based containers exported by PalmSens electrochemistry instruments. Nexus parses the Measurements/DataSet/Values structure and extracts each measurement curve as a separate scalar time-series (0Dts) signal with its own timestamps and units.

SRS RGA

Stanford Research Systems (SRS) Residual Gas Analyzer export files.

Property Detail
Extension .txt
Format Tab-delimited text
Signals produced Pressure vs Time: multiple scalar (0Dts) signals — one per channel; Histogram: single spectrum (1Dts)

SRS RGA .txt files are exported by the RGA Windows software that accompanies SRS RGA100, RGA200, and RGA300 series instruments. Nexus supports both scan types:

Pressure vs Time

Each monitored mass channel becomes a separate 0Dts time-series signal (e.g., Mass 18 – H₂O, Mass 28 – N₂). Timestamps are elapsed seconds from the experiment start time recorded in the file header.

Histogram

A single-snapshot mass spectrum is loaded as a 1Dts signal with a mass (amu) axis. The scan range (start mass to stop mass) and pressure values are extracted directly from the file.

Auto-detection

Nexus identifies SRS RGA files by checking that line 2 of the .txt file contains "Residual Gas Analyzer Software", then determines the scan type from section headers (Pressure vs Time Scan Setup or Histogram Scan Setup).

SenseAI TIFF

DENSsolutions SenseAI reconstruction output files.

Property Detail
Extension .tiff
Format Multi-page TIFF
Signals produced Image series (2Dts)

SenseAI TIFF files contain up to four pages per frame: reconstruction, import, reference, and mask. Timestamps are parsed from the filename pattern capture_YYYY-MM-DDTHH-MM-SS.mmm_SignalName.tiff.

Import modes

When loading SenseAI TIFF files, Nexus presents a dialog with two options:

  • Individual — Each file is loaded as a separate dataset.
  • Time Series — All files are merged into a single 2Dts image series, ordered by their filename timestamps.

Auto-detection

Nexus identifies SenseAI TIFF files by the capture_ filename prefix combined with the embedded timestamp pattern.

Velox EMD

ThermoFisher Velox electron microscopy data files.

Property Detail
Extension .emd
Format HDF5-based
Signals produced Image series (2Dts), spectra (1Dts), scalar data (0Dts)

Velox EMD files use the HDF5 container format. They can hold STEM images, HRTEM image series, EDS/EELS spectra, and associated scalar metadata channels. Nexus lazily loads EMD files — only metadata is read during import, and pixel data is loaded on-demand when a signal is added to the canvas. Timestamps are derived from detector-specific metadata (e.g. ExposureTime for imaging detectors, FrameTime for scanning detectors).

DM3 / DM4

Gatan DigitalMicrograph files.

Property Detail
Extensions .dm3, .dm4
Format Proprietary binary
Signals produced Images (2D), spectra (1D), image series (2Dts)

Nexus lazily loads DM3/DM4 files - only metadata is read during import, and pixel data is loaded on-demand when a signal is added to the canvas.

Single-file image merging

If a single DM file contains multiple 2D images with identical dimensions, they are automatically merged into an image series (2Dts). Images with different dimensions remain as separate signals.

Multi-file merging

When you select two or more DM3/DM4 files, Nexus offers to combine same-dimension images across all files into a single time series. See Merging Multiple DM3/DM4 Files for details.

Image adjustments

DM3/DM4 files may contain embedded display settings (brightness, contrast, gamma, colormap) stored by Gatan DigitalMicrograph. When such a signal is dropped onto the canvas, these settings are automatically applied. You can restore them at any time using the Dataset Defaults button in the Image Adjustments panel.

SER / EMI

TIA (FEI/ThermoFisher) series and metadata files.

Property Detail
Extensions .ser, .emi
Format Binary series with XML metadata
Signals produced Image series (2Dts), spectra (1Dts)

SER files contain the raw data series and EMI files hold the accompanying XML metadata. Nexus supports both older (v≤528, 32-bit offsets) and newer (v>528, 64-bit offsets) SER file versions, and handles both image (2Dts) and spectrum (1Dts) data types. When an EMI file is present alongside a SER file, additional acquisition metadata (microscope settings, detector configuration) is included in the signal metadata.