~~Hi~~

Probably Hi,

probably you're conducting your experiments with utilization of excessive digital resolution (points per Hz). For example, one can consider 2D COSY spectrum obtained with **2048** points in the direct dimension **(TD=2k)** and **1024** increments in the indirect dimension **(TD1=1k)** with real size of the spectrum of **1024** points in each dimension **(SI = SI1 =1k)**, as an outcome one obtains matrix of experimental data that consists **1024^2** elements (2nd order tensor). Each one of these matrix entries needs **8 bytes** to be digitally described.
Now it's time to do some math:

`File_Size = 1024*1024*8 Bytes = `~~(2^10)*(2^10)*(2^3)B ~~2*(2^10)*(2^3)B = (2^23)B = (8388608)B = 8 MB

Outcome of this calculation is the exact size of the ** *.ser** file. One can calculate it for all types of 2D spectra and outcome always will be in the form of

**2^n Bytes**. File sizes of higher dimensional spectra can be calculated analogously.

So if one wants to obtain for example 2D spectrum with final **8192** points in direct dimension and **8192** in indirect dimension (TD=16k, TD1=4k, SI=SI1=8k), must have in mind that file size will be:

```
FS= 2*(2^13)*8 B = (2^29) B = 536 870 912 B = 512 MB !!!
```

Algorithm for fast fourier transformation operates on DFT matrix, so the massive matrix requires more computing power and that equals, among other things, to long processing times of the spectrum.

I don't know which variant of DOSY you're using, but I presume that is casual 2D DOSY. Probably the cause of your problem it's a wrong setting of a few parameters :

*(Bruker TopSpin parameters)*

*aqcupars:*

*TD, TD1, AQ, DW, SW, SW1*

*procpars:*

*SI, SI1, Linear Prediction parameters.*

Please paste these mentioned above parameters of your DOSY experiments, and maybe we'll be able to help you (add also spectrometer 1H operating frequence).

Personally, I don't know unusua procedures that allows to process only fragments of 2D spectrum. Some sophisticated methods were introduced in high dimensional spectra processing with nonuniform sampling.

If you want to reduce the size of your files, you should in the first place choose the proper carrier wave frequency (SW) and adjust resolution (TD,SI,AQ,DW)according to your needs.

Best regards,

Arkadiusz Leniak