# Oneshot for Varian (G.A. Morris/M. Nilsson)

This page is a part of the user-editable NMR Wiki pulse sequence database.

Disclaimer: You are solely responsible for correct use of these materials on your instrument.

## Basic facts about Doneshot

Synopsis: DOSY pulse sequence using bipolar gradient pairs

Family: Diffusion experiments

 Code authors: Gareth A. Morris, Mathias Nilsson

## Introduction

The Oneshot sequence is suitable for "one-shot" acquisition (only one transient per gradient level), and is also a good general DOSY sequence. The pulse sequence is a more elaborated version of BPPSTE sequence, using bipolar pulse pairs. The refinements include a purge pulse in the diffusion delay, unbalanced gradient pulses in the bipolar pulse pairs as well as heating compensation gradients that are incremented as the diffusion gradients are incremented.

## Macros

#### setup_dosy

Enters a dialog to set-up the gradient array with equal steps in gradient squared. It is normally advisable to make even the first gradient level significant (e.g. 3G/cm)

#### makedosparams

Sets the parameter dosytimecubed $(\displaystyle \gamma^2 \displaystyle \delta^2 \displaystyle \Delta ')$ when the pulse sequence is run. Dosytimecubed is a convenient parameter when fitting the data e.g. to produce a DOSY plot.

NB! These macros are compatible with VnmrJ2.3 or older.

## Software that can process DOSY data

• The DOSY package of Vnmr and VnmrJ

Note: expand this list, by creating pages for programs and adding category links "Software" and "DOSY" to those pages.

## RF parameters

• pw,tpwr,tof - 90o pulse, its power level and transmitter offset
• satdly,satpwr,satfrq - length, power and offset of saturation pulse (used if satmode='y')

• gzlvl1 - amplitude of diffusion encoding gradient
• kappa - unbalance factor for the bpp pulses. The default of 0.2 is almost always suitable
• gt1 - total length of gradient encoding pulses gradient (split into two equal length bipolar pulses)
• gzlvl3, gt3 - amplitude and duration of the spoiler/purge gradient
• gzlvl_max - safety parameter, will trigger error message if gzlvl1*(1+kappa) > gzlvl_max

## Delays

• del - diffusion delay
• gstab - gradient recovery delay

## Flags

• delflag - value 'y' turns on the "diffusion" part of the pulse sequence, 'n' - turns it into a one pulse 1D experiment
• wet - value 'y' turns on Wet water suppression
• satmode - value 'y' turns presaturation on